Tunnel diode load for ultra-fast low power switching circuits

DETAILED DESCRIPTION The key element of my invention is the use of a tunnel diode for rapid discharging of a capacitor in a switching circuit.
The tunnel diode has a low resistance in the tunnel regime at low forward bias voltages, but it has a high resistance at moderately higher forward bias voltages when tunneling through the p-n barrier has ceased, and the ordinary diode current involving carrier transport across that barrier is still quite small.
At a steady state input voltage which turns the switching device in a switching circuit on, most of the power supply voltage extends over the tunnel diode load device, which then is in the high resistance state.
After the switching device current is turned off by a change in its input voltage, the voltage across the tunnel diode drops, and the diode resistance decreases from the high value in the non-tunnel regime to the low value in the tunnel regime.
This provides low power consumption in the steady state when the switching device is turned on, as well as fast switching speed for the transient following the turn-off of the switching device.
The preferred switching device of my invention is an n-channel enhancement mode GaAs field effect transistor.
The low power consumption of my circuit is enhanced by using a low supply voltage of the order of only one volt.
This voltage level provides a voltage drop of a few tenths of a volt across the switching transistor in its on-state, the remaining several tenths of a volt biasing the tunnel diode to the afore-mentioned high resistance state.
Thus the node voltage between the switching transistor and the tunnel diode is a few tenths of a volt when the transistor is turned on and becomes the power supply voltage of about one volt in the steady state when the transistor is turned off.
Since this node voltage is the input voltage to the switching device of the next stage, and level shifting is to be avoided, since it affects speed and power consumption adversely, we require a switching transistor which is turned off at a few tenths of a volt input, but turned on by about one volt