Direct Coupled Biasing Circuit for High Frequency Applications

摘要

This invention eliminates the need for “capacitor coupling” or “transformer coupling,” and the associated undesirable parasitic capacitance and inductance associated with these coupling techniques when designing high frequency (˜60 GHz) circuits. At this frequency, the distance between two adjacent stages needs to be minimized. A resonant circuit in series with the power or ground leads is used to isolate a biasing signal from a high frequency signal. The introduction of this resonant circuit allows a first stage to be “directly coupled” to a next stage using a metallic trace. The “direct coupling” technique passes both the high frequency signal and the biasing voltage to the next stage. The “direct coupling” approach overcomes the large die area usage when compared to either the “AC coupling” or “transformer coupling” approach since neither capacitors nor transformers are required to transfer the high frequency signals between stages.

主权项

1. An apparatus comprising:
a magnitude of a first current through a first transistor generates a first biasing voltage; a control loop configured to monitor the first biasing voltage and to generate a second biasing voltage; and a first resonant parallel LC load couples the second biasing voltage to an input of a second transistor to control a second current through the second transistor; and an output power drive characteristic of the second transistor is scaled in direct proportion to an adjustment of the magnitude of the first current.