A Receive-Band-Noise Estimation Method and Its Application to a WCDMA Band 11/21 GaAs-BiFET MMIC Power Amplifier Module

This paper proposes a simple but relatively accurate, receive (Rx)-band-noise estimation method for wideband code division multiple access (WCDMA) handset heterojunction bipolar transistor MMIC power amplifier module (PAM) design. The method is based on small-signal and two-tone large-signal simulations, calculating Rx-band noise and helping circuit designers comprehend noise contributions under a large output power operation. Its effectiveness is verified through the simulations and measurements of a WCDMA band 11/21 MMIC PAM featuring an LC trap circuit placed at the base terminal of the first stage. This trap is designed to resonate at the difference frequency between the transmit- and Rx-bands. The PAM accommodating switchable-amplifier chains for triple-power modes-high power mode (HPM), mid-power mode (MPM), and low-power mode (LPM)-is fabricated using our in-house GaAs BiFET process. Measurements conducted under 3.4 V and 1450-MHz-band WCDMA (Third Generation Partnership Project Release 99, 3GPP R99) modulated signals show an Rx-band noise level of less than -136 dBm/Hz and power gain as high as 30 dB at a high output power (P
_out
) of 29 dBm. The measured noise level is in good agreement with that of the proposed estimation. The measurements also show that the PAM achieves power-added efficiency (PAE) as high as 41% at the P
_out
of 29 dBm while maintaining the ±5-MHz-offset adjacent channel power ratio (ACLR1) below -40 dBc in the HPM. The PAE values of 22% at P
_out
of 18 dBm and 17% at 7 dBm are obtained in the MPM and LPM, respectively, with the same ACLR1 levels.