This paper presents a Pulse-Amplitude Modulation (PAM) backscatter modulator based on BiCMOS technology chip for Wireless Power Transmission (WPT) applications. Both chip design and measurement setup considered are described. The circuit presents a modulator capable of performing PAM modulation in a wide range of frequencies. Then, to evaluate the communication performance, a low-cost Software Defined Radio (SDR) was used to demodulate the received modulated signals. In a wide range of power levels (-60 to -10 dBm) and different data rates in the chosen frequencies, the circuit performance (FM-band, ISM band, DVB-T band, and GSM band) was demonstrated.