JPH0648975Y2 - Magnetostatic wave delay linear oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is, for example, a VCO (voltage-controlled oscillator:
The present invention relates to magnetostatic wave delay line oscillators (voltage controlled oscillators) and the like, and relates to magnetostatic wave delay line oscillators with SSB (single sideband) phase noise improved.

<Prior Art> First, a magnetostatic wave delay element will be briefly described. When two transducers made of a metal conductor and a magnetic material are placed close to each other in a uniform magnetic field, and a high-frequency current is passed through one of the two transducers, spins in the magnetic material near the transducer fluctuate. The fluctuation propagates as a magnetostatic wave and propagates, and a high-frequency dielectric current due to the fluctuation of the spin flows in the other transducer. Since the propagation speed of spin fluctuations changes according to the strength of the magnetic field, the device has a variable delay time.

FIG. 3 shows a state in which a magnetic field is applied to the magnetostatic wave delay element by a magnetic field applying means (not shown), the frequency signal flowing in the loop is taken into the spectrum analyzer through the coupler, and the oscillation frequency characteristic is measured. 1 is a magnetostatic wave delay element, 2 is an amplifier, 3 is a coupler, and 4 is a spectrum analyzer. These are connected in a loop and the oscillation frequency changes according to the applied magnetic field.

FIG. 4 shows a spectrum of frequencies oscillated when a constant magnetic field is applied to the oscillator having the above-mentioned configuration. According to this figure, the frequency of fo is the peak of power (Ps), and the power before and after this is gently reduced. The ratio of the total power of the entire signal and the power density of a certain frequency away from the peak (in practice, the power of the peak frequency and the power of the frequencies before and after it ... In the figure, the power Ps of the frequency fo and the frequency fm away from fo Power ratio Pssb / P
s) is called SSB phase noise (fm), but the smaller the ratio, the better.

The SSB phase noise (fm) can be calculated by the following formula.

L (fm) = − 177 + F−Pc −20log (2π · τg · fm) [dBc / Hz]… where F; amplifier noise figure [dB] Pc; amplifier input power (static wave delay element output power) )… [DBm] Pc = Pin-l Pin = Input power of magnetostatic wave delay element [dBm] l = Loss in magnetostatic wave delay element [dB] τg; Group delay time in magnetostatic wave delay element (speed at which energy is transmitted) )… [Ns] fm; Frequency deviated from the center frequency The above equation is Proc.1985 Ultrasonics Sympo., P16
The formula shown in “Phase Noise Characteristics of MSW Device” by KW Chang, W. Isak, Kunz and others described in 3 to 168 l (fm) = − 177 + logF−10LogPm−20Log (2πτ ・ f
m) is an arrangement.

It is known that the loss l in the magnetostatic wave delay element is 1 = 76.4 × 10 ^-3 · ΔH · τg (issued in February 1988 (Proc.I
EEE, 76, No2, P171−187 ... W. Isak “Magnetostatic Wave T
echnology: A Review ").

Therefore, L (fm) = − 177 + F−Pin + 76.4 × 10 ⁻³ · ΔH · τg −20log (2π · τg · fm).

ΔH = full width at half maximum of magnetic resonance of magnetic material used in magnetostatic wave delay element <Problem to be solved by the invention> According to the above equation, the term of 76.4 × 10 ^-3 · ΔH · τg increases as τg increases, The term −20log (2π · τg · fm) becomes smaller as τg becomes larger. Therefore, from the expression SS
It can be seen that the B phase noise has a minimum value for τg.
That is, given parameters such as F, Pin, ΔH, τg
There is a problem that L (fm) cannot be made lower than a certain value even if various values are changed.

In Fig. 5, the center frequency is 2 GHz, and the SSB phase noise (that is, L (fm) of L at the position deviated from this frequency by 10 KHz is L
(10 KHz), the magnetic field strength ΔH is 0.85 Oe, the noise figure of the amplifier is 2.5 dB, and the input power to the magnetostatic wave delay element (P
in) is used as a parameter to show the relationship between SSB phase noise and group delay time. According to the figure, for example Pin = -5 dBm
, SSB phase noise cannot be smaller than -118 dBc / Hz], and Pin = +20 dBm cannot be smaller than -143 [dBc / Hz].

The present invention has been made in view of the above problems of the prior art.
It is an object of the present invention to realize a magnetostatic wave delay linear oscillator with small SSB noise by connecting magnetostatic wave delay elements and amplifiers in series in multiple stages.

<Means for Solving the Problems> The configuration of the present invention for solving the above problems includes a plurality of magnetostatic wave delay elements arranged in a uniform magnetic field and outputs from the magnetostatic wave delay elements. It is composed of a plurality of amplifiers for amplifying and one coupler, the output of the magnetostatic wave delay element is input to the amplifier, the output of the amplifier is connected to the input side of the magnetostatic wave delay element of the next stage, and the magnetostatic wave delay By repeatedly inputting the output of the element to the amplifier of the next stage and connecting in series in a loop form in n stages, the output terminal of the amplifier and the magnetostatic wave delay element in the loop composed of the magnetostatic wave delay element and the amplifier The coupler is placed between the input side and the frequency oscillation signal in the loop so as to extract the frequency oscillation signal, and the group delay time of the magnetostatic wave delay element is set so as to obtain the minimum SSB phase noise. Phase noise is reduced It is.

<Example> Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a magnetostatic wave delay linear oscillator of the present invention. In the figure, the same elements as those in FIG. 3 are designated by the same reference numerals and the duplicate description is omitted, but in the present embodiment, the magnetostatic wave delay elements 1a, 1b, 1c and the amplifiers 2a, 2b, 2c are integrated on the substrate. The output side of the magnetostatic wave delay element is connected to the input terminal side of the amplifier, and the output side of this amplifier is wired in a loop to the input transducer side of the magnetostatic wave delay element.

The coupler 3 is arranged in the middle of the wiring forming the loop and takes out the frequency oscillation signal flowing in the loop.

In the frequency oscillator with the above configuration, 10KH from the center frequency
The phase noise at the z-shifted position can be expressed by the following equation.

L (10KHz) = − 177 + F−Pc −20log (2π · 3τg · 10KHz) That is, if the combination of the magnetostatic wave delay element and the amplifier is three sets as shown in FIG. τg
Is 3τg, the SSB phase noise (L) is small.

Moreover, since the input power Pc of the amplifier is Pc = Pin−1 Pin−76.4 × 10 ⁻³ · ΔH · τg, L (10KHz) = − 177 + F−Pin + 76.4 × 10 ⁻³ · ΔH · τ
g −20log (2π · 3τg · 10KHz) becomes, and when generalized to connect n amplifiers and magnetostatic wave delay line, L (10KHz) = -177 + F-Pin + 76.4 × 10 ^-3 · ΔH · τ
g −20log (2π · nτg · 10KHz) That is, if the combination of the magnetostatic wave delay element and the amplifier is n sets, τg included in the term of −20log to becomes nτg, so that L becomes small.

Therefore, the phase difference noise L (10 KHz) can be reduced by setting τg to the minimum SSB phase noise as shown in FIG. 5 and then increasing n.

2 (a) and 2 (b) are perspective views showing another configuration example. In this example, a magnetostatic wave delay element, an amplifier, is formed on a silicon or sapphire substrate by using a known semiconductor technique or photolithography technique. A wiring and a coupler connecting these are formed, and the substrates are laminated to form an n-stage oscillator. With such a configuration, downsizing is possible.

<Effects of the Invention> As described above, according to the present invention, a plurality of magnetostatic wave delay elements arranged in a uniform magnetic field and a plurality of amplifiers for amplifying the outputs from the magnetostatic wave delay elements, The output of the magnetostatic wave delay element is input to the amplifier, the output of the amplifier is connected to the input side of the magnetostatic wave delay element of the next stage, and the output of the magnetostatic wave delay element is further connected to the amplifier of the next stage. Is repeatedly connected to n stages in series in a loop form, and the coupler is provided between the output terminal of the amplifier and the input side of the magnetostatic wave delay element in the loop composed of the magnetostatic wave delay element and the amplifier. Is arranged so that the frequency oscillation signal in the loop is taken out and the group delay time of the magnetostatic wave delay element is set to be the minimum SSB phase noise. Implemented magnetostatic wave delay linear oscillator To it can be.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetostatic wave delay line oscillator according to the present invention, FIG. 2 is a perspective view showing another configuration example, and FIG.
FIG. 4 is a configuration diagram showing a conventional example, FIG. 4 is an explanatory diagram of SSB phase noise, and FIG. 5 is a diagram showing a relationship between SSB phase noise and group delay time. 1a to 1c ... Magnetostatic wave delay element, 2a to 2c ... Amplifier, 3 ... Coupler.

Claims (1)

[Scope of utility model registration request] 1. A magnetostatic wave delay element comprising a plurality of magnetostatic wave delay elements arranged in a uniform magnetic field, a plurality of amplifiers for amplifying outputs from the magnetostatic wave delay elements, and a single coupler. The output is input to the amplifier, the output of the amplifier is connected to the input side of the magnetostatic wave delay element of the next stage, and the output of the magnetostatic wave delay element is connected to the amplifier of the next stage repeatedly to form n loops. Frequency oscillating signal in the loop by connecting the coupler between the output terminal of the amplifier and the input side of the magnetostatic wave delay element in the loop composed of the magnetostatic wave delay element and the amplifier connected in series. The magnetostatic wave delay linear oscillator is characterized in that the SSB phase noise is reduced by setting the group delay time of the magnetostatic wave delay element to be the minimum SSB phase noise.