JPS59103416A - Phase shift circuit - Google Patents

Abstract

PURPOSE:To obtain a flat frequency characteristic over a broad band by applying a desired phase shift with a single frequency signal and obtaining a mixed output between the single frequency signal phase-shifted in this way and an input signal so as to phase-shift the input signal. CONSTITUTION:The input signal at an input terminal 1 is given to one input of the 1st mixer 6a. A local oscillator 7 is a signal source generating a single frequency signal and the output single frequency is branched into two by a distributor 8. One output signal from the distributor 8 is given to the other input of the 1st mixer 6a, the output of the mixer 6a passes through the 1st filter 10 and is given to one input of the 2nd mixer 6b. The other output signal of the distributor 8 is given to the other input of the 2nd mixer 6b via a narrow band- phase shift circuit 9. The output of the mixer 6b passes through the 2nd filter 11 and is led to the output terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a phase shift circuit for frequencies in the VHF and UHF bands. In particular, the present invention relates to a phase shift circuit having flat frequency characteristics for wideband signals.

[Description of prior art]

Conventionally, this type of circuit has been constructed as shown in FIG. 1
2 is an input terminal, 2 is a 90° divider, 3a and 3b are balanced modulators, 4 is a combiner, and 5 is an output terminal.

The signal V applied to the input terminal l is divided into two signals VS/σ and jvs/ with a 90° phase difference by the 90° distributor 2.
Distribute to J. When this signal is weighted by cos θ and sin θ by the balanced modulators 3a and 3b, respectively, v
g'cos θ/child, jv, sin θ/ren. When these are combined by the combiner 4, the output is VsCose71L ti Vs ・Si'L e
M, and the phase θ weighted to the balanced modulators 3a and 3b
You will get a signal rotated by

However, since it is difficult to obtain flat frequency characteristics over a wide band with the 90° distributor 2 used here, for example, in the 140 Mllz band, the practical bandwidth is 30 Mllz.
However, if the signal V is a wideband signal, it is difficult to shift the phase accurately over the entire bandwidth. 90° again
Since the distributor uses an LC resonant circuit or a distributed constant circuit, it has the disadvantage that it is difficult to miniaturize it by integrating it into an integrated circuit.

[Purpose of the invention]

An object of the present invention is to provide a phase shift circuit that has flat frequency characteristics over a wide band and can be manufactured into a compact structure.

[Features of the invention]

The present invention obtains a single frequency signal, performs a desired phase shift operation on the single frequency signal, and obtains a mixed output of the phase shifted single frequency signal and the input signal. It is characterized by phase shifting.

[Explanation based on an embodiment] FIG. 2 is a circuit configuration diagram of an embodiment of the present invention. 1 is an input terminal, 5 is an output terminal, 6a and 6b are mixers, 7 is a local oscillator, 8 is a divider, 9 is a narrow band phase shift circuit, and ]0.11 is a filter.

The input signal at input terminal 1 is applied to one input of first mixer 6a. The local oscillator 7 is a signal source that generates a single frequency signal, and the output single frequency signal is branched into two by a divider 8. One output signal of the distributor 8 is given to the other input of the first mixer 6a. The output of this first mixer 6a is passed through the first filter 10 by 1ffl,
It is applied to one input of the second mixer 6b. Distributor 8
The other output signal is applied to the other input of the second mixer 6b via the narrowband phase shift circuit 9. The output of the second mixer 6b is passed through the second filter 11 to the output terminal 5.
guided by.

The input signal of the input terminal 1 is a wideband signal containing communication information. Let its angular frequency be ω8. The output signal of the local oscillator is a single frequency signal whose angular frequency is ω. The first filter 10 is a bandpass filter with an angular frequency ωε+ω. The second filter 11 is a bandpass filter with an angular frequency ω.

In the device configured in this way, the output of the local oscillator 7 is branched into two by the divider 8, and one of the outputs is phase-shifted by the narrowband phase shift circuit 9, so that each signal VLI°kICO3ωL
We obtain t1 VL 2 =kt cos (ωLt + θ).

kl is a constant. When 2cosω,1 is added to one of these VLI and the input signal vG= to the mixer 6a, the output of the mixer 6a is VL
t・VS=kx k2cosωL1, and two frequency components of ωL±ωS are generated on both sides of the local oscillation frequency. k2 is a constant. One of these, for example, ωL
When the +ω8 component is extracted by the filter 10 and added to the mixer 6b together with the other two-branched signal VL2, the output is as follows. Of these, the first term signal is passed through the filter 11.
When extracted, a signal 1; kl kx Oos (us = -0) obtained by phase-shifting the input signal Vs = 2 cos ω, 1 by an angle θ is obtained.

Here, the narrowband phase shift circuit 9 only needs to have a phase shift function at the single output frequency of the local oscillator, and wideband performance is not required. Therefore, the circuit can be constructed using small and simple elements such as a CR phase shifter. Also, the mixer 6a,
Since the filter 6b has a wider band than the 90° divider, the operating frequency is determined by the pass band of the filter 10, and the band can be easily widened. For example, if the local oscillation frequency is 500 Mllz,
If the passband of the filter 10 is 300 to 420 Mllz, the operating frequency is 80 to 200 Mllz (bandwidth 120 Mllz), which is 115 Mllz according to the prior art.
~155 Mllz (bandwidth: 30 Mllz), it is possible to significantly widen the bandwidth.

Even if the difference component ω1--ω is extracted by the filter lO, it will be the output of the mixer 6b, and similarly, the component of the angular frequency ω appears phase-shifted in the opposite direction by the angle θ, so This can be extracted by the filter 11.

In the circuit shown in FIG. 2, an amplifier can be inserted in the middle of the circuit in order to amplify the signal level or to reduce mutual interference between the circuits.

In the above example, the phase shift circuit 9 may be inserted into either side of the signal split into two by the divider 8, or may be inserted into both sides.

The local oscillator frequency can be set either higher or lower than the input signal frequency.

[Explanation of application examples]

The present invention can be applied to wideband combiners and distributors that combine or branch signals at arbitrary phases, which has been difficult to widen for the same reason. FIG. 3 shows an example in which the present invention is applied to this distributor. Here, 12 is a divider that branches the input signal into two, and 13a and 13b are phase shift circuits according to the present invention. To operate this, the signal vS applied to the input terminal 1 is divided by a divider 12, and each phase shift circuit 13
Phase shift operation is performed by a and 13b. Therefore, the phase portion of the difference in phase shift amounts added by the phase shift circuits 13a and 13b is obtained at the output terminals 14a and 14b. Although having such a configuration, it is possible to construct a distributor having a phase shifting function that can be easily miniaturized and widened in bandwidth, similar to the one explained in FIG. 2.

In addition, by using 14a and 14b as input terminals and using ■ as an output terminal, and connecting the input/output terminals 1a and 5a of the phase shift circuit 13a in reverse, and also connecting the phase shift circuit 13b in reverse, a synthesizer having a phase shift function can be obtained. can get. Furthermore, the local oscillation signals of the two phase shift circuits 13a and 13b can be shared.

[Explanation of effects]

As explained above, according to the present invention, since the input signal is not directly phase-shifted, but the local oscillation signal is phase-shifted, a narrow-band phase shifter can be used. As this phase shifter, a small and simple one such as a CR phase shifter is sufficient, and the phase shifter can be integrated into an integrated circuit. Furthermore, since the frequency characteristics mainly depend on the characteristics of the mixer, it is possible to obtain flat frequency characteristics over a significantly wider band than with conventional phase shift circuits.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a conventional phase shift circuit. FIG. 2 is a configuration diagram of a circuit according to an embodiment of the present invention. FIG. 3 is a configuration diagram of a circuit according to an application example of the present invention. ■, 1a, 1b--input terminal, 2/90° distributor,
3a, 3b...Balanced modulator, 4...Mixer, 5.5
a, 5b...output terminal, 6a, 6b...mixer, 7
...Local oscillator, 8...Distributor, 9...Narrowband phase shift circuit, 10.11...Filter, 12...Distributor,
13a, 13b...phase shift circuit, 14a, 14b
...Output terminal. 0

Claims (1)

[Scope of claims] a first mixing means for mixing the input signal with the first output signal of the means for giving a first filter that extracts a signal of either the frequency or the difference frequency; and a second filter that mixes the output signal of the filter with the second output signal of the means for providing the phase difference. A phase shifting circuit comprising: mixing means; and a second filter for extracting a signal having a frequency equal to the input signal obtained at the output of the second mixing means.