H High IP3 MMIC LNA at 900 MHz Application note for the BGA2011 The BGA2011 is a MMIC LNA for cellular applications at 900 MHz that require good linearity, like CDMA. The MMIC is produced by the single metal DPO Philips process and is packaged in a 6-pin SOT363. The circuit is equipped with control pin that can set the amplifier to low current-low noise mode or to high current-high linearity mode and/or disable (off) mode. This report describes an application in which the LNA can be tuned for gain and input IP3. At 900 Mhz, the input IP3 is adjustable between 2 dBm at 19 dB gain and 7 dBm at 16 dB gain. H Circuit description The LNA consists of one RF stage. The RF transistor is biased with a controlled bias circuit that can set the collector current of RF transistor to the desired value. The trade-off between noise/linearity and current consumption can be found by setting the collector current of RF transistor. In this way it is possible to make a low noise mode and a high linearity mode. Moreover, the control pin serves as an enable/disable pin that can switch the supply current off. In order to increase the linearity of LNA, a series feedback has to be introduced, made by stripline, from the emitter of the RF transistor to ground. Measured results conditions: demo board without u-stripline (0 mm) freq=900 MHz; Vsupply= 3V; temp=25 deg Vc Isupply S21 Input return loss Output return loss IIP3 NF Pout1db compression [V] 1.0 1.4 1.6 1.9 2.3 2.7 3.0 [mA] 1.4 3.5 4.6 6.5 11.1 13.9 15.5 [dB] 11.9 16.6 17.5 18.3 19.0 19.1 19.2 [dB] 4.3 8.7 10.0 11.1 11.3 11.2 11.2 [dB] 5.4 8.1 8.9 10.2 11.4 11.8 12.0 [dBm] -21 -9 -6 -5 +2 +3 +4 [dB] 1.1 1.3 1.3 1.4 1.5 1.6 1.7 [dBm] -17 -9 -6 -2 +3 +6 +7 conditions: demo board with 1.5 mm u-stripline freq=900 MHz; Vsupply= 3V; temp=25 deg Vc Isupply S21 Input return loss Output return loss IIP3 NF Pout1db compression [V] 1.0 1.4 1.6 1.9 2.3 2.7 3.0 [mA] 1.4 3.5 4.6 6.5 11.1 13.9 15.5 [dB] 10.3 13.8 14.4 15.1 15.7 15.8 15.8 [dB] 6.9 14.6 18.0 21 18.6 17.7 17.4 [dB] 6.8 9.5 10.4 11.3 12.7 13.0 13.1 [dBm] -9 -2 +1 +4 +7 +8 +8 [dB] 1.1 1.4 1.4 1.5 1.6 1.7 1.8 [dBm] -16 -7 -5 -2 +4 +7 +8 note: IIP3 - input IP3 measured with ∆f=100 kHz and Pin<-28 dBm Isupply - is a total supply current from 3 Volt supply source 2 H Application diagram Vc C5 C3 C4 Vc C6 Vs L2 Vs Bias Circuit L1 RFoutput Out RFinput In C2 C1 SOT363 gnd u-strip 0-1.5 mm C6 u-stripline L1 C1 C2 x C4 L2 x x C3 C5 <-------20mm-------> <-------20mm-------> Demo board Component C1 C2 C3 C4 C5 C6 L1 L2 Value Typ 100 pF Philips 0603 100 pF Philips 0603 22 nF Philips 0603 5.6 pF Philips 0603 22 nF Philips 0603 2x 100 nF Philips 0805 10 nH TDK 0603 8.2 nH TDK 0603 notes: 1. There are 4 types of demo board layouts available: no stripline (0 mm), 0.5 mm, 1.0 mm and 1.5 mm stripline; marked L0, L05, L10 and L15. 2. The u-stripline to ground is optimized for each length. For no stripline (0 mm), the metal under pin 5 and 6 is filled with vias to the ground plane to reduce inductance. For the stripline versions, the stripline ends in 2 vias. 3. The standard demo board also needs three 0 Ù SMD’s (0603) at the spots marked with an X. Additional components to adjust the biasing can be placed at these spots. 3