H Philips Semiconductors B.V. Gerstweg 2, 6534 AE Nijmegen, The Netherlands Report nr. Author Date Department : RNR-T45-97-B-006 : T.F. Buss : Jan. 6 1997 : P.G. Transistors & Diodes, Development 900MHz LOW NOISE AMPLIFIER WITH THE BFG403W Abstract: This application note contains an example of a Low Noise Amplifier with the new BFG403W Double Poly RF-transistor. The LNA is designed for a frequency f=900MHz, VSUP~1.5V, ISUP~1mA. Measured performance at f=900MHz: Noise Figure NF~1.8dB, gain S21 ~16dB. Appendix I: 900MHz LNA circuit Appendix II: Printlayout and list of used components & materials Appendix III: Measured Performance 1 H 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. Because this LNA has an extreme low power-consumption, it is well suited for pager front-end applications. Designing the circuit: The circuit is designed to show the following performance: transistor: BFG403W Vce~0.9V, Ic ~1mA, VSUP~1.5V freq=900MHz Gain~16dB NF<=1.8dB VSWRi<1:3 VSWRo<1:2 Designing the layout: A lay-out has been designed with HP-MDS. Appendix II contains the printlayout. Measurements: Measurements of the total circuit are done (Appendix III). 2 H Philips Semiconductors B.V. Appendix I: Schematic of the circuit C3 C4 R1 +VSUP C2 R3 R4 Coil_2 Coil_1 R2 OUT 50Ω C5 IN 50Ω C1 W1 BFG403W µS4: µS4 L1 L2 µS4 D1 L3 W2 Figure 1: LNA circuit 900MHz LNA Component list: 900MHz LNA Component list: Component Value Purpose, comment R1 Bias (coll.-base) 13 kΩ R2 in series with coll. for better S22, stability and reducing gain. 150 Ω R3 RF blocking 22 Ω R4 Bias, series with coll., cancelling hFE spread 390 Ω C1 1.2 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 1.2 pF Output match (collector to output) Coil_1 15 nH Input match (base-bias) Coil_2 15 nH Output match (collector-bias) µs4 (see next µ-stripline Emitter-induction table) 3 H 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 1.0mm length µ-stripline; Z0~48Ω (PCB: εr ~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 H Philips Semiconductors B.V. Appendix II: Printlayout and list of used components & materials RFin C1 C7 C5 C6 L1 R2 C2 C4 L2 R1 Vsup R4 R3 C3 900MHz LOW NOISE AMP. Figure 2: Printlayout Comment: C6 and C7 are not used in this LNA. 900MHz LNA Component list: Component: PCB R1 R2 R3 R4 C1 C2 C3 C4 C5 L1 L2 Value: FR4: εr ~4.6 13 kΩ 150 Ω 22 Ω 390 Ω 1.2 pF 27 pF 27 pF 100 nF 1.2 pF 15 nH 15 nH size: H=0.5mm 0603 Philips 0603 Philips 0603 Philips 0603 Philips 0603 Philips 0603 Philips 0603 Philips 0805 Philips 0603 Philips 0805CS Coilcraft 0805CS Coilcraft 5 RFout H Philips Semiconductors B.V. Appendix III: Measured Performance BFG403W; f=900MHz 2 VSUP [V] ISUP [mA] |S 21| [dB] Gain |S 12| [dB] Isolation VSWRi VSWRo Noise Figure [dB] 1.1 1.5 1.7 -27 -30 -31 3.0 2.7 2.8 1.6 1.5 1.5 1.7 1.8 2.0 0.5 1.0 1.5 13 16 17 2 6