A Power Amplifier for Space Applications with Improved Phase Resolution
Gulloch, W; Goss, M; Schryber, P; Seymour, D; Gulloch, W
EADS Astrium

This paper presents improved phase resolution results for L & S Band Power Amplifiers for Space applications. This development, supported under ARTES 4, builds on previous work which obtained 1.8 degree phase resolution at L-Band from a 15 Watt Power Amplifier. The new Power Amplifiers features variable output power from 14 to 22 Watts at optimal efficiency together with greatly improved phase resolution. The previous Power Amplifier used a 7 Bit, all digital, MMIC phase shifter while the new design uses an 8 Bit device. Using this new DPS, 7 Bits are driven conventionally with a digital voltage while one of the Bits is driven by an analogue control voltage. This enables device performance to be significantly improved compared with an all digital approach. The combination of digital and analogue control has demonstrated nearly 1 degree of phase resolution at L-Band and S-Band. In addition to improved phase resolution the new SSPA’s feature; a fully updated MMIC control section, driver and final PA stage as well as a new digital control circuit. This phase resolution technique and digital control scheme can also be applied at higher frequencies.