Measurement Results for the Frequency-Tunable CMOS RF Power Amplifie - Linear CMOS RF Power Amplifiers for Wireless Applications - page 103

Table 7.1 Measured
S parameters for the
stand-alone PA. Values for
the PA matched at 5.2 GHz

SP 2.4 GHz 3.7 GHz 5.2 GHz

S 11 (dB) − 3 . 7 − 4 . 5 − 22 . 8

S 22 (dB) − 6 . 3 − 7 . 7 − 24 . 2

S 21 (dB) 8 . 9 7 . 8 8

S 12 (dB) − 22 . 5 − 20 . 8 − 16 . 5

Fig. 7.4 Measured 2-tone power gain at 5.2 GHz for the stand-alone RF PA

We can see that the maximum linear output power delivered by the stand-alone
PA in a simultaneous conjugate match condition is about 14 dBm (25 mW). The
PAE at this distortion level is 9.7%. These values show that the stand-alone PA
operates satisfactorily.

7.3 Coupled Inductors Characterization

A test structure composed of the coupled inductors configured as a 3-terminal device
was designed as shown in Fig. 7.6 . The purpose was to allow an on-wafer character-
ization with a probe station. One terminal of each winding was used as an RF port,
whereas the second terminal of each winding was grounded. Figure 7.7 shows a
photograph of the test structure. A Ground-Signal-Ground (GSG) pad configuration
was employed. This procedure of characterization is based on [ 11 ] and is suitable
for 2-port measurements. For pad de-embedding, an open structure was used.