On the stability of millimeter-wave power amplifiers

Abstract

-In this paper, we discuss issues affecting highfrequency power amplifier stability. Two methods for simulating K-factor stability in a monolithic millimeter-wave integrated circuit (MMIC) power amplifier will be discussed. Both methods will be used to predict the occurrence of millimeter-wave oscillations ( Ka-band and above) in a Wband power amplifier. We present experimental results confirming the simulation data, and discuss how the methods may be applied to eliminate instabilities in MMIC power amplifiers.

Stability investigation for InP DHBT mm-wave power amplifier

“…This method is usually used to detect a potential low frequency instability arising from biasing circuitries but it also works well at higher frequencies []. As shown in Figure , the RF ports are terminated with 50 Ω, while the detection ports are inserted at the biasing circuitries: one is applied to the base biasing line of the devices, while the other one is applied to the collector.…”

“…For more complicated circuits where circuit instabilities are hidden due to the circuit symmetry, there are several other techniques reported for the instability detection. Based on two‐port K ‐Δ s pair, it has been shown that the potential odd‐mode instability can be detected using push‐pull simulation setups , which force odd‐mode operations between combined cells using ideal transformers at power combining points. Another method for stability analysis is the system identification [] by calculating driving point impedances within the circuits.…”

“…Based on two‐port K ‐Δ s pair, it has been shown that the potential odd‐mode instability can be detected using push‐pull simulation setups , which force odd‐mode operations between combined cells using ideal transformers at power combining points. Another method for stability analysis is the system identification [] by calculating driving point impedances within the circuits. The frequency response of driving point impedances is derived from an auxiliary current or voltage source used to inject a small‐signal perturbation into the circuits at critical nodes [].…”

Detecting and avoiding odd-mode parametric oscillations in microwave power amplifiers

“…The most suitable approach for eliminating oddmode oscillations relies on the connection of resistances between the different paralleled branches of the ampli-fier [1][2][3][4][5][6][7]14]. The insertion of resistances between the transistors that oscillate with a phase difference of 180°a llows us to eliminate odd-mode oscillations.…”

Medium power amplifiers covering 90-130 GHz for the ALMA telescope local oscillators

“…Sonnet EM simulator was used to model complicated geometries such as the four-way output combiner of Chip 2. Also, a complete stability analysis was performed on both amplifier designs, using the methodology outlined in [11]. It was found necessary to include odd-mode suppression resistors in the combiners to prevent odd-mode oscillations.…”