JPH03144998A - Sampling head - Google Patents

Abstract

PURPOSE:To improve high frequency characteristics and to facilitate monolithic constitution by applying sampling pulses to diodes for sampling through a coplanar waveguide. CONSTITUTION:When a sampling pulse is applied to a signal conductor P2 at time t1, all diodes D11-D1a turn on and the signal input on a signal conductor S11 is sent to a point Q. Short-circuit transmission lines L1 and L2, however, short-circuits X3 and Y11, and X3 and Y12 to each other, so a pulse beings to fall at time t2. At time t3, a voltage is 0 and the diodes D11-D18 turn off. Namely, the signal input is connected to the point Q in the period t1-t3, a signal can be sampled. The input signal and sampling pulses are transmitted by the coplanar waveguide to the sampling diodes, so that monolithic constitution becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to improving the characteristics of a sampling head for an ultra-high frequency oscilloscope.

<Prior Art> FIG. 5 is a circuit configuration diagram showing a sampling head for a conventional ultra-high frequency oscilloscope (14.H).

Grove; IEEE Trans, on H,T,T
, Vol, t4TT-14, No, t2゜DEC, 1
966, p629-635. Fig. 9). XI
2. Very short rise time (for example, width 100n)
When a sampling pulse (with a rising edge of 10 ps) is applied, the two sampling diodes D1゜D
turns on, and the signal input is the cathode terminal voltage of diode D1 and the 7-node terminal voltage V of diode D2.
Appears as 2. However, since the above pulse is short-circuited by Yl and Y2, it falls immediately and the diode D1.
The time that D2 is on becomes very short (for example, several L)
ops).

Therefore, for example, instantaneous values of microwave signal input up to around 20 GHz can be sampled. Here, RL is a terminal resistance for signal input.

Voltages V and V are 1 through resistors R and R2, respectively.
2 1 is connected to amplifier A1 and averaged output V.

bawl.

<Problems to be Solved by the Invention> In an ultra-high frequency oscilloscope, signal input and sampling input are normally input to the sampling head via a coaxial connector. Therefore, when realizing the sampling head with a monolithic circuit using a semiconductor substrate, it is preferable to use a coplanar waveguide as shown in FIG.
As shown in the figure, a signal conductor 2 and ground conductors 31 and 32 are provided on a substrate 1, and ultra-high frequency signals are transmitted with low loss.

However, in the conventional example shown in Fig. 5, the line between Y and Yl that transmits the signal input can be realized by a cograin wave guide, but the sampling pulse input is provided with one line each for the signal and the ground, so it is not possible to use a coaxial Difficult to connect with connector.

That is, if the signal is transmitted using a coplanar waveguide up to just before the sampling head and then connected to two transmission lines midway, a loss will occur at the connection point and the high speed of the sampling pulse will be impaired.

The present invention was made to solve these problems, and an object of the present invention is to realize a sampling head that has excellent high frequency characteristics and can be easily made monolithic.

Means for Solving the Problems> The first aspect of the present invention relates to a sampling head that samples a signal input using a sampling pulse, and is characterized by sampling the signal input and the sampling pulse through a coplanar waveguide. The signal conductor of the coplanar waveguide that transmits the sampling pulse input to the sampling diode and the two ground conductors are short-circuited by a transmission line.

The second aspect of the present invention relates to a sampling head that samples a signal input using a sampling pulse, and is characterized by a first coplanar waveguide that propagates the signal input, and a second coplanar waveguide that propagates the sampling pulse input. a waveguide, two terminating resistors connected between a signal conductor of the first coplanar waveguide and a ground conductor, a signal conductor of the second coplanar waveguide and a signal conductor of the first coplanar waveguide; a first diode connected between;
a second diode connected between a signal conductor of the first coplanar waveguide and two ground conductors of the second coplanar waveguide; and a signal conductor and two ground conductors of the second coplanar waveguide. and a short-circuit transmission line that short-circuits between the two diodes, and the signal input is configured to obtain a sampling output based on the voltage appearing through each diode when each diode is turned on by a sampling link pulse input.

Effect> Since the signal input and the sampling pulse are applied to the sampling diode via the coplanar waveguide, high frequency characteristics are improved and monolithization is facilitated.

<Example> The present invention will be explained in detail below using the drawings.

FIG. 1 is a configuration circuit diagram showing a first embodiment of a sampling head according to the present invention. S7t, Git'G1□ are respectively the signal conductors and the first .S7t of the first coplanar waveguide which propagate the signal input. Second ground conductor, RLl
, RL2 are first and second terminating resistors connected between the signal conductor $11 and the ground conductor G11''1°, P2.
G21. G22 constitute the second coplanar waveguide for propagating the sampling pulse input, respectively the signal conductor and the first . The second ground conductor, D S-D, is the first diode bridge for sampling connected between the signal conductor P2 and the ground conductor G21, and D15 to D18 are connected between the signal conductor P2 and the ground conductor G22. A second diode bridge for sampling, L and L2 are connected to the signal conductor P2 and the two ground conductors G21 of the second coplanar waveguide.
This is a short-circuit transmission line that short-circuits between 2 degrees and converts the step pulse applied to P2 into an impulse. Here, the diode D13゜D1□ constitutes a first diode connected between the signal conductor P2 of the second coplanar waveguide and the signal conductor S11 of the first coplanar waveguide, and the diode D14' D18 constitutes a first diode connected between the signal conductor P2 of the second coplanar waveguide and the signal conductor S11 of the first coplanar waveguide. signal conductor S11 of the coplanar waveguide and two ground conductors G21 of the second coplanar waveguide. ' 22 respectively. Termination resistor RL1=RL for signal input. For example, 50
When using the Ω-based first coplanar waveguide, the resistance becomes 100Ω.

The operation of the above m-precept sampling head will now be described. FIG. 2 is a time chart showing the change in voltage at one point X3 on the signal conductor P2 corresponding to the sampling pulse input.
00 ns width> is applied to the signal conductor P2, all of the diodes D11 to D18 are turned on, and the signal input on the signal conductor S11 is transmitted to the Q point. However, there is a short circuit between X3Y11 and X3Y1□ on the transmission line L1. Since it is shorted at L2, the pulse begins to fall at time t2.

Here, the broken line in the figure shows the pulse waveform in the case where there is no short-circuit transmission line L, L2 for comparison. At time t, point X3
The voltage becomes O, and all diodes D11 to D1 are turned off. That is, 18 from t to t3
1 period (e.g. 10ps)
Since the signal input is connected to point Q, sampling of the signal is possible.

According to the sampling head having such a configuration, since both the signal input and the sampling pulse input are transmitted to the sampling diode through the coplanar waveguide, it is easy to make it monolithic. Furthermore, there is no loss due to conversion, and the bandwidth of the sampling head is widened.

In the above embodiment, the short-circuit transmission lines L and L can be omitted if short impulses generated in the curved circuit can be applied to the signal conductor P2.

Furthermore, the diodes D13, D17', Dll, and D15 can each be made into one diode while maintaining the balance of the circuit, such as the balance of on-resistance.

FIG. 3 is a configuration circuit diagram showing a second embodiment of the sampling head according to the present invention, in which two diodes are used instead of a diode bridge. The same parts as in FIG. 1 are given the same symbols and the explanation is omitted. A capacitor C is connected between the signal conductor P and the ground conductor G21, and a forward diode D13. D1 14, capacitor C1□ are connected in series, and capacitor C13,
Forward diode D17. D18. Capacitor C14
are connected in series. Here, capacitors C11 to C
14 is used to cut direct current. When the sampling pulse is applied, the diode D13. D14. D
1□, D18 is turned on, and the signal input is diode D1
3 anode terminal, diode D14 cathode terminal,
They are output from the anode terminal of diode D17 and the cathode terminal of diode D18, respectively, and are connected to resistor R1.
1'R12'R13' R14 is applied to the amplifier A1, and the output V is obtained by averaging voltage differences due to diode drops and the like.

FIG. 4 is a configuration circuit diagram showing a third embodiment of the sampling head according to the present invention, in which D13 and D1□ and C11 and C13 in FIG. 3 are made common. In other words, diodes D13 and D1□ are made common to form a diode D19,
By making capacitors C11 and 013 common, capacitor C1
It is set at 5. The operation is similar to that in FIG. 3, but the three outputs from the diode terminals are averaged through resistors R15 to R1□.

In addition, in the circuits of FIGS. 3 and 4, the ground conductor G1
1" 1° and G21" 2° are separated, but they can also be connected. Other features are the same as in FIG.

<Effects of the Invention> As described above, according to the present invention, high frequency characteristics are excellent;
A sampling head that can be easily made monolithic can be realized with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a configuration circuit diagram showing a first embodiment of the sampling head according to the present invention, FIG. 2 is a time chart showing the operation of the device shown in FIG. 1, and FIG. 3 is a second embodiment of the sampling head according to the present invention. FIG. 4 is a configuration circuit diagram showing a third embodiment of the sampling head according to the present invention, and FIG. 5 is a configuration circuit diagram showing a conventional example of the sampling head.
A circuit diagram, FIG. 6, is an explanatory diagram of a coplanar waveguide. 311...signal conductor of first coplanar waveguide, G11. G12...Ground conductor of the first coplanar waveguide, RLl, RL. ...terminal resistor, P2
...signal conductor of the second coplanar waveguide, D
13, D1□, D19...first diode, G21
．． G22...Ground conductor of second coplanar waveguide, D14. D18...Second diode, L1
．． L2...Short transmission line.

Claims (2)

[Claims] (1) In a sampling head that samples a signal input using a sampling pulse, the signal input and the sampling pulse are respectively applied to a sampling diode via a coplanar waveguide, and the signal conductor of the coplanar waveguide that transmits the sampling pulse input and two A sampling head characterized in that a transmission line is used to short-circuit between ground conductors. (2) In a sampling head that samples a signal input using a sampling pulse, the first coplanar waveguide propagates the signal input, the second coplanar waveguide propagates the sampling pulse input, and the first coplanar waveguide. two terminating resistors connected between the signal conductor and the ground conductor of the guide; and a first termination resistor connected between the signal conductor of the second coplanar waveguide and the signal conductor of the first coplanar waveguide.
a signal conductor of the first coplanar waveguide and two of the second coplanar waveguide.
a second diode connected between the signal conductor of the second coplanar waveguide and the two ground conductors, and a short-circuit transmission line short-circuited between the signal conductor of the second coplanar waveguide and the two ground conductors, and each diode is turned on by a sampling pulse input. A sampling head characterized in that the sampling head is configured to obtain a sampling output based on a voltage that appears through each diode when a signal input is applied.