JPS60263532A - synthesizer receiver - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention uses a voltage controlled oscillator as a local oscillator,
In a synthesizer receiver that uses this voltage controlled oscillator as a component to form a phase, lock, IV loop (hereinafter referred to as PLL), a so-called FM negative feedback method is used in which a part of the receiver output is frequency modulated on the local oscillator. regarding a synthesizer receiver. <Prior Art> Generally, a synthesizer receiver has a structure as shown in FIG. In Figure 4, (It> is a high frequency amplifier, (2) is a mixer, (3) is an intermediate frequency amplifier, and (4) is a demodulator. A voltage controlled oscillator is used as the local oscillator (5), The phase of the signal obtained by dividing this local oscillation output signal by the frequency divider (6) and the signal obtained by dividing the frequency of the reference signal from the reference signal oscillator (7) by the programmable frequency divider (8) is The comparator (9) performs a phase comparison, and the phase comparison output is passed through a low-pass filter (10) to remove high frequency components, and then the low frequency component is input to the local oscillator (5) as a frequency control voltage to drive the PLL. The receiving frequency is determined by the contents preset in the programmable frequency divider (8) (a tuning code corresponding to the receiving frequency), and is normally determined by the tuning code generated by the tuning code generator (11). Tuning operation is performed by presetting a code in the programmable frequency divider (8) and changing the division ratio N. Also, the tuning code from the tuning code generator (11) is A plurality of segment groups (14B) for displaying each digit of the received frequency and other information on the frequency display (13) after being converted into a decimal frequency display segment signal by the code conversion/drive circuit (12); (14,b)
,,1. Nisoresore will be supplied. On the other hand, the output of the demodulator (4) is fed through the amplifier (15) to the local oscillator (5) to form an FM negative feedback loop, and a part of the demodulated output is used to frequency modulate the local oscillator (5). The local oscillation frequency is made to follow the frequency modulation of the received wave. 1 like this. In the M negative feedback method, the frequency deviation in the intermediate frequency band is compressed as well as that of the received wave, so the intermediate frequency amplifier (3) can be made narrowband without increasing distortion. It has the feature that the threshold level can be improved without sacrificing the S/N ratio. <Problems to be Solved by the Invention> Although the conventional techniques described above basically have excellent features, there are further problems to be solved. That is, the local oscillator (5) is LO as shown in FIG.
It can be modeled with a resonant circuit, and the capacitance of the varicap C+ for changing the oscillation frequency changes according to the oscillation frequency, while the modulation varicap C2 maintains the same capacitance against changes in the oscillation frequency. The capacitance changes only in response to the modulation signal. When feedback is applied to such a local oscillator (5), the amount of feedback changes depending on the oscillation frequency, and the higher the oscillation frequency, the larger the amount of feedback. Specifically, the FM band in Japan is 76.0~90°9.
MHz, and the local oscillation frequency is 65.3 to 79,
In a local oscillator varying in the range of 3 MH7,
When the feedback amount of the demodulated output is set to 6 dB (receiving frequency 83 MHz), as shown in Figure 7, the feedback amount within the 1M band is approximately 4.5 dB (minimum receiving frequency 76 MHz).
~7.5dB (maximum receiving frequency 90MHz), minimum receiving frequency f min and maximum receiving frequency f
There is a difference of about 3dB at max. In FIG. 7, the one-dot chain line represents the characteristic after phase correction by the phase correction circuit (16). In the above configuration, the reception frequency (local oscillation frequency)
Since the amount of feedback changes within a range of approximately 3 dB depending on the . The present invention aims to improve these problems to be solved. <Means for Solving the Problem> The present invention provides a high frequency amplifier, a mixer, an intermediate frequency amplifier, a demodulator, a local oscillator, and a signal obtained by dividing the local oscillation output signal of the local oscillator, and a reference signal, which are pulled on the programmer. A phase, lock, /L/ - the channel selection code from the channel selection code generation circuit is preset in the programmable frequency divider to determine the reception frequency, and the output of the demodulator is connected to the amplifier. In a synthesizer receiver that forms an FM negative feedback loop that feeds back to the local oscillator and modulates the frequency, the received frequency is detected from the tuning code output from the tuning code generation circuit, and the detection output is used to control the amplifier. The configuration is such that the gain of the receiver is changed depending on the reception frequency. As a specific means of the present invention, a code conversion circuit converts a tuning code into a decimal digital signal, detects a reception frequency from this digital signal, and uses this detection output to adjust the gain of the amplifier according to the reception frequency. detecting a receiving frequency band (the entire receiving frequency band is divided into a plurality of bands) from the digital signal;
Means for changing the gain of the amplifier in multiple stages according to the reception frequency band based on the detection output, the amplifier having a continuously variable gain type, and the tuning code corresponding to the reception frequency using a D/A converter. There is a means for converting the signal into an analog signal and using the analog signal to continuously change the gain of the amplifier according to the receiving frequency. <Operation> According to the present invention, the gain of the amplifier can be changed continuously or stepwise depending on the reception frequency or reception frequency band, and the feedback amount of the FM negative feedback loop can be changed depending on the reception frequency or reception frequency band. It can be changed continuously or stepwise depending on the situation. <Example> Hereinafter, an example of the present invention will be explained with reference to the drawings.
Components equivalent to those of the conventional example shown in FIG. 6 are designated by the same reference numerals, and their explanation will be omitted. <Embodiment 1> In Fig. 1, (17) is an amplifier, and an operational amplifier (1
The non-inverting input (19 &) of 8) is used as the input terminal for the demodulation output, the inverting input (19b) is connected to the output of the operational amplifier (18) via the first resistor R1, and the inverting input (19&) of ) are connected in series, the second and third resistors R2,
The gain of the amplifier (17) is changed by grounding the connection point P of the second and third resistors R2 and Ra through the switching circuit (2o). It is composed of That is, since the gain A of the amplifier (17) is given by A=1+-□ 1.2 10Ra, the gain A' when the connection point P is grounded
becomes IA'=1+-(>A)2. The switching circuit (20) is composed of a known circuit,
For example, the base terminal of a first PNP transistor (21) whose emitter and collector are biased with a predetermined voltage is used as the input terminal for the detection signal, and the collector output is connected between the connection point P and the ground. It has a configuration in which it is connected to the gate terminal of the second field effect transistor (22). . (23) is a receiving frequency band detector that is supplied with the tuning code output from the tuning code generation circuit (11) and detects the receiving frequency band from this tuning code, and its detection output is sent to the switching circuit (20). ) of the first transistor (2
1) is input to the base terminal. The reception frequency band detector (23) is FMz<n> in Japan from '76.0 to '90. QMHz in two reception frequency bands (
76.0-79.9MHz, 80.0-90.0M
Hz), the reception frequency band is detected by the following detection method.・The reception frequency is 76.0 to 90 as the tuning code is as follows.
If each digit of OM Hz is given as a BCD code expressed as a binary number, (l QMHz digit) 2 '(MHz digit) 2 (0,
IMHz digit] 2 (the subscript represents a binary number) If the receiving frequency is in the range of 76.0 to 79.9 MHz, the 10 MHz digit code of the tuning code is [01
11) 2f a), and the receiving frequency is 80.0 to 90
If it is in the range of MHz, the channel selection code lOM Hz
I) Digit code is (1000)2 or [1001]
It becomes 2. Therefore, 4 of the 10MHz digit code of the tuning code
digit

The receiving frequency band can be detected by detecting [0] and [1], and in the case of (0), it is 76, 0 to 79.91'
l (HZ band, [1] is 8o, o~90, 0M
Hz band teal. The relationship between the receiving frequency band and its detection output is as follows: When the receiving frequency band is 76,0 to 79.9 W (z, low level zu(L
) 80, 0-90. 'OMHz I:), the high level [■] is selected. In the above configuration, its operation will be explained below. First, when the receiving frequency band is 76.0 to 79.9 MHz, the detection output of the receiving frequency band detector (23) is
L), so the first and second transistors (21)
, (22) are both conductive and the connection point P is grounded, so the gain A' of the amplifier (17) is x = 1+ --- 2. Next, the reception frequency band is 80.0-90.0M
In the case of Hz, the operation is opposite to the above, the first and second transistors (2I) and (22) maintain the cutoff state, and the gain A of the amplifier (17) is as follows, F M negative feedback The loop feedback amount is 76.0 to 8
It is large in the 9.9MHz receiving frequency band, and conversely, 80,
, O ~ 90.0 MHz receiving frequency band It is small. Such a change in the amount of feedback is inherent in the local oscillator (5), that is, it compensates for and cancels the change in the amount of feedback according to the oscillation frequency. It is something to do. Therefore, the total feedback amount of the FM negative feedback loop is 7
6.0~79.9MHz, 80.0~90.0MHZ
7. Since both bands are almost the same, the separation characteristics are as shown in FIG. 4, and the rate of change in separation with respect to the reception frequency is significantly improved compared to the conventional example. <Example 2> In this example, the segment group (1
4a), (14'b), . The detector (23) is not required. This will be explained in FIG. , 5bSSc, . , , After being converted into Sg, each segment of the segment group (11) representing the lQMHz digit of the reception frequency) a, b,
c, , 1g, respectively. Here, focusing on the segment group (14B), segment g is 76.0 to 79°9 MH
It does not light up and display in the reception frequency band of 80.0 to 90.
．． It can be seen that the light is displayed in the OM Hz receiving frequency band. That is, the reception frequency band can be detected by detecting the segment signal Sg that drives the segment g, and this segment signal 8g is low level (L) when the reception frequency band is 76.0 to 79.9 MHz.
80, 0-90.0 MHz, high L//</L
7(I()).Then, this segment signal Sg is input to the main notching circuit (20) in the same manner as in Example 1. <Example 3> In this example, the feedback of the FM negative feedback loop is determined according to the receiving frequency. This is a continuously variable gain amplifier in which the gain changes continuously, and the tuning code from the tuning code generation circuit (11) is used as a control voltage to be sent to the D/A converter (24). A signal whose level changes continuously according to the receiving frequency is supplied, which is converted into an analog signal by the following. <Effects of the Invention> Since the present invention has the above configuration, it has the following effects. (1) The feedback amount of the FM negative feedback loop changes depending on the reception frequency or reception frequency band, and this change in feedback amount is inherent to the local oscillator (5), that is, feedback according to the oscillation frequency. (2) Therefore, the total amount of feedback of the FM negative feedback loop is almost the same for the receiving frequency band. (2) Therefore, the amount of separation for the receiving frequency is The rate of change is significantly smaller than that of the conventional example, and the separation characteristics are improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of the synthesizer receiver of the present invention, FIGS. 2 and 3 are diagrams showing the configuration of another embodiment of the same, and FIG. 4 is a diagram showing the seven-region characteristics, FIG. 5 is a model of a local oscillator, FIG. 6 is a diagram showing the configuration of a conventional synthesizer receiver, and FIGS. 7 and 8 are characteristic diagrams. (1) is a high frequency amplifier, (2) is a mixer, (3) is an intermediate frequency amplifier, (4) is a demodulator, (5) is a local oscillator, (
6) is a frequency divider, (7) is a reference signal oscillator, (8) is a programmable frequency divider, (9) is a phase comparator, (10) is a low-panel filter, (conversion/drive circuit), (13) is a Frequency display, (17) is amplifier, (2o) is switching circuit, (23) is reception frequency band detector, (24) is D/A
It is a converter. Patent Applicant Onkyo Co., Ltd. Pu 23 Zhoulang Soft 4 [21 Quasi 5th Page 7 Zhou Langbok No. S Round Proceedings Amendment (Spontaneous) November 19, 1981 1, Indication of Case 1988 Patent Application No. 120337 2, Title of the invention: Synthesizer receiver 3, Person making the amendment 6, Contents of the amendment (1) From page 6, line 17 to page 7, line 3 of the specification, “The output of the demodulator is converted into an amplifier. This is a configuration in which the gain of the amplifier is changed in accordance with the reception frequency using this detection output.'' is corrected as follows. "In a synthesizer receiver forming an FM negative feedback loop in which the demodulated output of the demodulator is fed back to the local oscillator to apply frequency modulation, the FM negative feedback loop is activated by the detection output of the reception frequency or reception frequency band. It has a configuration in which the gain is changed according to the reception frequency or i reception frequency band.'' (2) On page 7, line 7 of the specification, ``Amplifier J rFM negative feedback loop or within this FM negative feedback loop. An amplifier
Correct to. (3) "Amplifier" on page 7, line 11 of the specification is replaced with "FM negative feedback loop or an amplifier within this FM negative feedback loop."
Correct to. (4) "Amplifier" on page 7, line 20 of the specification is replaced with "FM negative feedback loop or an amplifier within this FM negative feedback loop."
Correct to. (5) The following statement is inserted between page 12, line 15 and page 12, line 16 of the specification. ``Furthermore, in this embodiment, the gain of the amplifier circuit constituted by the operational amplifier (18) is constant, and the output thereof is divided by a dividing circuit consisting of a series circuit of resistors, so that the gain of the FM negative feedback loop can be reduced by several times. This will be explained in Fig. 9. (31) is a well-known amplification circuit (29) that is composed of an operational amplifier (1B) and has a constant gain, and a plurality of resistor series circuits. This is a variable gain amplifier consisting of a gain adjustment circuit (3o) consisting of a dividing circuit and an electronic switch for selectively switching the dividing circuit, and corresponds to the amplifier (17) of <Embodiment 1>. The adjustment circuit (30) includes a series circuit of a fourth resistor R4, a fifth resistor R5 and a first electronic switch (26), a series circuit of a sixth resistor R6 and a second electronic switch (27), and a series circuit of a sixth resistor R6 and a second electronic switch (27). The series circuit of resistor R7 of 7 and the second electronic switch (28) is connected in parallel, and each resistor R4, R5 connected in common
, R6 and R7 are grounded via an eighth resistor R8,
A connection point between this eighth resistor R8 and each of the resistors R4, R5, R6, and R7 is connected to a local oscillator. In addition, a fourth resistor R4
, the other ends of the first electronic switch (26), the second electronic switch (27), and the first electronic switch 28 are connected to the amplifier circuit (29), and the gain adjustment The demodulated output amplified by the amplifier circuit (29) is input to the circuit (30). On the other hand, the reception frequency band detector (23) outputs a detection output corresponding to the reception frequency band divided into three, and this detection output is sent to the first, second, and Third electronic switch (26), (27), (
28) and the first, second, and third electronic switches (26) corresponding to the detected reception frequency bands.
, (27), and (28) are brought into conduction. (6) The scope of claims is amended as follows. rHigh frequency amplifier (1), mixer (2), intermediate frequency amplifier (3), demodulator (4), local oscillator (5), and a signal obtained by dividing the local oscillation output signal of the local oscillator (5) A phase comparator (9) compares the phase of the reference signal with a signal obtained by dividing the frequency of the reference signal by a programmable frequency divider (8), and inputs the phase comparison output to the local oscillator (5) via a low-pass filter (10). The channel selection code generator (11) outputs the channel selection code from the programmable frequency divider (8).
) to determine the reception frequency, forming an FM negative feedback loop in which the demodulated output of the demodulator (4) is fed back to the local oscillator (5) to apply frequency modulation. (7) FIG. 9 is added, in which the gain of z't, -goo is changed according to the reception frequency or reception frequency band in accordance with the detection output of the reception frequency or reception frequency band. that's all

Claims (1)

[Claims] High frequency amplifier (1), mixer (2), intermediate frequency amplifier (
3), a demodulator (4), an i-part oscillator (5), and a signal obtained by dividing the local oscillation output signal of the local oscillator (5) and a reference signal by a programmable frequency divider (8). A phase comparator (9) compares the phases of the two with a phase comparator (9), and the output of the phase comparison is inputted to the local oscillator (5) via a Rhopan filter (10). , the channel selection code output from the channel selection code generator (11) is passed through the programmable frequency divider (8).
FM negative feedback non-op is formed by feeding back the demodulated output of the demodulator (4') to the local oscillator (5) to apply frequency modulation. In the synthesizer receiver, a variable gain amplifier (17) is inserted into the FM negative feedback loop, and the reception frequency or reception frequency band is detected from the tuning code, and the detection output is used to connect the amplifier (17). ) A synthesizer receiver characterized in that the gain of the receiver is changed according to the receiving frequency band.