Philips Semiconductors B.V. Gerstweg 2, 6534 AE Nijmegen, The Netherlands Report nr. Author Date Department : RNR-T45-96-B-1025 : T.F. Buss : 10 Dec. 1996 : P.G. Transistors & Diodes, Development IMPROVED IP3 BEHAVIOUR OF THE 900MHz LOW NOISE AMPLIFIER WITH THE BFG425W UPDATE OF REPORT RNR-T45-96-B-771 Abstract: This application note contains an example of a Low Noise Amplifier with the new BFG425W Double Poly RF-transistor. The LNA is designed for a frequency f=900MHz, VSUP~3.8V, ISUP=10mA. Measured performance at f=900MHz: Noise Figure NF~1.7dB, gain S21 ~17dB and the input IP3=+3dBm. Appendix I: 900MHz LNA circuit Appendix II: Printlayout and list of used components & materials Appendix III: Results of simulations and measurements 1 Philips Semiconductors B.V. Introduction: With the new Philips silicon bipolar double poly BFG400W series, it is possible to design low noise amplifiers for high frequency applications with a low current and a low supply voltage. These amplifiers are well suited for the new generation low voltage high frequency wireless applications. In this note an example of such an amplifier will be given. This amplifier is designed for a working frequency of 900MHz. Designing the circuit: The circuit is designed to show the following performance: transistor: BFG425W V ce=2V, Ic=10mA, V SUP~3.5V freq=900MHz Gain~18dB NF<=1.6dB IP3>0dBm (input) VSWRi<1:2 VSWRo<1:2 In the simulations the effect of extra RF-noise caused by the SMA-connectors was omitted, so in the practical situation the NF is ~0.1dB higher. This LNA is also optimised for the highest IP3. The IP3 can be optimised by: I. an extra series C-decoupling of the base to the ground II. increasing IC With the solution I. an extra component is necessary, and with solution II, the Noise Figure of the LNA increases and the optimum source impedance also. The in- and outputmatching is realised with a LC-combination. Also extra emitter-inductance on both emitterleads (µ-strips) are used to improve the matching and the Noise Figure. Designing the layout: A lay-out has been designed with HP-MDS. Appendix II contains the printlayout. Measurements: Simulations (with realistic RF-models of al used parts) and measurements of the total circuit (epoxy PCB) are done (Appendix III). 2 Philips Semiconductors B.V. Appendix I: Schematic of the circuit C3 C6 C4 R1 +VSUP C2 R3 R4 Coil_2 Coil_1 R2 OUT 50Ω C5 IN 50Ω C7 C1 W1 BFG425W µS4: µS4 L1 µS4 L2 D1 L3 W2 Figure 1: LNA circuit 900MHz LNA Component list: 900MHz LNA Component list: Component Value Purpose, comment R1 8.2 kΩ Bias (coll.-base) R2 10 Ω in series with coll. for better S22, stability and reducing gain. R3 22 Ω RF blocking R4 150 Ω Bias, series with coll., cancelling hFE spread C1 8.2 pF Input match (input to base) C2 27 pF 900 MHz short (L1 to ground) C3 27 pF 900 MHz short (L2 to ground) C4 100 nF RF decoupling collector bias C5 22 pF Output match (collector to output) C6 100 nF To improve IP3 (by decoupling LF IP3 products) C7 3.3 pF Output match, stability (collector to emitter) Coil_1 22 nH Input match (base-bias) Coil_2 12 nH Output match (collector-bias) µs4 (see next µ-stripline Emitter-induction table) 3 Philips Semiconductors B.V. µS4 Emitter inductance of µ-stripline and via-hole (see on former page: Schematic of the circuit): Name Dimension Description L1 2.5mm length µ-stripline; Z0~48Ω (PCB: ε r ~4.6, H=0.5mm) L2 1.0mm length interconnect stripline and via-hole area L3 1.0mm length via-hole area W1 0.5mm width µ-stripline W2 1.0mm width via-hole area D1 0.4mm diameter of via-hole 4 Philips Semiconductors B.V. Appendix II: Printlayout and list of used components & materials RFin C1 C5 C7 C6 L1 R2 C2 C4 R1 L2 Vsup R4 R3 C3 900MHz LOW NOISE AMP. Figure 2: Printlayout 900MHz LNA Component list: Component: PCB R1 R2 R3 R4 C1 C2 C3 C4 C5 C6 C7 L1 L2 Value: FR4: ε r ~4.6 8.2 kΩ 10 Ω 22 Ω 150 Ω 8.2 pF 27 pF 27 pF 100 nF 22 pF 100 nF 3.3 pF 22 nH 12 nH size: H=0.5mm 0603 Philips 0603 Philips 0603 Philips 0603 Philips 0603 Philips 0603 Philips 0603 Philips 0805 Philips 0603 Philips 0805 Philips 0603 Philips 0805CS Coilcraft 0805CS Coilcraft 5 RFout Philips Semiconductors B.V. Appendix III: Results of simulations and measurements Conditions: V SUP=3.7V, IC=10mA, f=900MHz Simulation (HP-MDS): |S21|2 [dB] 17.2 2 |S12| [dB] -28.0 VSWRi 2.2 VSWRo 1.7 Noise Figure [dB] 1.6 IP3 [dBm] (input) +1.3 Measurements PCB: 17.3 -28.3 2.5 1.8 1.7 +3 Comment: note 1 ∆f=200KHz, note 2 note 1: The Noise Figure of the PCB is higher than the simulations (~0.1 dB). This is caused by the influence of the SMA-connectors and the microstrips on the epoxy PCB. note 2: The IP3 of the PCB is higher than the simulations. This can be explained by the deviation of the Spice parameters, used in the IP3 simulations, from the sample transistor-parameters used in the LNA. W=Wvia CMP230 MSVIA CMP286 MSVIA L=Lvi SUBST=s10mi a model cap.100nF L=1 nH C=1 nF l SUBST=s10mi OD=0.4 W=Wvia mm L=1 nH SUBST=s10mi l OD=0.4 mm l L=Lvi W=Wvia CMP287 MSTL R=0.3 OH C=100 nF SUBST=s10mi LOW NOISE AMP. WITH BFG425W@2V/10mA model cap.100nF l R1=22 OH SUBST=s10mi CMP236 MSTL l CMP405 MSTL SUBST=s10mi L=L3 SUBST=s10mi l SB1/BFG425W@2V/10mA CMP203 cmc_0603_phi W=Wvia L=Lvi l SUBST=s10mi a CMP281 cmc_0603_phi W=W3CMP408 L=L3MSTL SUBST=s10mi l SUBST=s10mi L=0.5 mm W=0.5 mm SUBST=s10mi l CMP394 coilcraft_l1008 CMP358 MSTL CMP197 cmc_0603_phi W=W50_Ohm L=6 mm l SUBST=s10mi 1 2 l 1 2 CMP431 SUBST=s10mi R_nor l L=L4 W=W4 CMP438 cmc_0603_phi CMP359 MSTL CMP266 MSVIA l Ccmc=Cout CMP403 MSTL L=0.5 mm W=0.5 mm CMP5 MSSUBSTRATE PORTNUM=2 CMP270 PORT_SPAR R=50 JX=0 SUBST=s10mi Ccmc=Ccex ER=4.6 HU=1.0E+3 m l MUR=1 T=35um COND=5.8e07 H=0.5mm ROUGH=10 um AGROUND TAND=0.02 CMP350 MSTL CMP351 MSTL W=0.5 L=L1 SUBST=s10mi mm W=0.5 L=L1 SUBST=s10mi mm l l W2=0.5 CMP250 MSTAPER mm W2=0.5 W1=Wvia_e SUBST=s10mi L=L2 SUBST=s10mi W1=Wvia_e L=L2 l l CMP180 MSVIA W=Wvia_e OD=0.4 mm CMP252 MSTAPER mm SUBST=s10mi CMP210 MSVIA W=Wvia_e OD=0.4 mm SUBST=s10mi Figure 3: HP-MDS simulation circuit 6 SUBST=s10mi CMP227 MSTL l SUBST=s10mi l Ccmc=Contkop L=0.5 mm W=0.5 mm _cs CMP257 TWOPORT DATA=DEBBY_425_2V_10m_1c.spar.SP.,freq=freq CMP383 R1=Rout MSTL Ccmc=Cin CMP18 PORT_SPAR smd l W=W50_Ohm L=6 mm CMP401 PORTNUM=1MSTL R=50 JX=0 L=3 mm W=0.5 mm CMP409 MSTL Lx=Lout W=W3 l l AGROUN CMP406 MSTL CMP399 coilcraft_l1008 Lx=Li n L=100 uH l 1 2 R1=11 k smd _cs 1 2 CMP429 R_nor W=0.5 mm L=0.5 mm SUBST=s10mi R=0.3 OH CMP428 R_nor Ccmc=Contkop CMP235 L R1=39 OH 1 2 CMP430 R_nor CMP419 R l CMP263 C CMP264 R W=Wvia CMP417 L CMP418 C a CMP289 cmc_0603_phi CMP265 L CMP231 MSTL AGROUND l OD=0.4 mm W=Wvia