AN11228: BGA301x Wideband Variable Gain Amplifier Application
Application note for designing a wideband CATV Variable Gain Amplifier using BGA3015/BGA3018 amplifiers and BAP70Q PIN diode attenuators with 20dB dynamic range.
Overview
This application note describes the implementation of a wideband Variable Gain Amplifier (VGA) suitable for CATV line-up applications. The design utilizes NXP BGA3015 and BGA3018 drop amplifiers integrated with a BAP70Q quad PIN diode attenuator. The circuit provides a 20 dB gain control dynamic range and flat gain performance between 40 MHz and 1003 MHz with 75 Ohm input/output impedance. The document includes a detailed evaluation board schematic, PCB layout requirements for FR4 substrates, and a complete Bill of Materials. It also provides extensive test data including S-parameters, K-factor stability, noise figure, and distortion measurements such as CTB, CSO, and XMOD at both 5V and 8V supply levels.
Use Cases
- CATV network line-up amplifiers
- Optical receiver RF signal conditioning
- Wideband signal attenuation and amplification
- RF dynamic range management in 75 Ohm systems
Topics
Referenced Parts
Yageo
L7 0 Ω (Jumper) 1 Yageo RC0402FR-070RL; R5, R8 0 Ω (Jumper) 2 Yageo RC0402FR-070RL
861V509ER6
Bomar
J1, J2 75Ω F-connector 2 Bomar 861V509ER6
RC0402FR-71K2L
Yageo
R4, R7 1200 Ω 2 Yageo RC0402FR-71K2L
RC0402FR-72K2L
Yageo
R6 2200 Ω 1 Yageo RC0402FR-72K2L
RC0402FR-71K2L
Yageo
R4, R7 1200 Ω 2 Yageo RC0402FR-71K2L Digikey 311-1.20KLRCT-
RC0402FR-72K2L
Yageo
R6 2200 Ω 1 Yageo RC0402FR-72K2L Digikey 311-2.20KLRCT-
| 90121-0766 | Molex | J3 Header 6 1 Molex 90121-0766 |
| BLM15HD182SN1D | Murata | L2, L6, L9 Choke 3 Murata BLM15HD182SN1D |
| GRM1555C1H101JZ01D | Murata | C4, C13 100 pF 2 Murata GRM1555C1H101JZ01D |
| GRM1555C1H271JA01D | Murata | C10 270 pF 1 Murata GRM1555C1H271JA01D |
| GRM155R71E103KA01D | Murata | C1, C2, C3 C6, C7, C8 C9, C11, C12 C15 10 nF 10 Murata GRM155R71E103KA01D |
| LQG15HN8N2J02D | Murata | L4 8.2 nH 1 Murata LQG15HN8N2J02D |
| LQG15HS3N9S02D | Murata | L1, L10 3.9 nH 2 Murata LQG15HS3N9S02D |
| LQH31HNR88K03L | Murata | L3, L5, L8 880 nH 3 Murata LQH31HNR88K03L |
| BAP70Q | NXP | U2 BAP70Q 1 NXP BAP70Q |
| BGA3015 | NXP | U3 BGA3015 1 NXP BGA3015 |
| BGA3018 | NXP | U1 BGA3018 1 NXP BGA3018 |
| RC0402FR-070RL | Yageo | L7 0 Ω (Jumper) 1 Yageo RC0402FR-070RL; R5, R8 0 Ω (Jumper) 2 Yageo RC0402FR-070RL |
| RC0402FR-07300RL | Yageo | R2, R10, R11 300 Ω 3 Yageo RC0402FR-07300RL |
| RC0402FR-07470RL | Yageo | R1, R3, R9 470 Ω 3 Yageo RC0402FR-07470RL |
| BLM15HD182SN1D | Murata | L2, L6, L9 Choke 3 Murata BLM15HD182SN1D Digikey 490-5196-1-ND |
| GRM1555C1H101JZ01D | Murata | C4, C13 100 pF 2 Murata GRM1555C1H101JZ01D Digikey 490-3458-1-ND |
| GRM1555C1H271JA01D | Murata | C10 270 pF 1 Murata GRM1555C1H271JA01D Digikey 490-1294-1-ND |
| GRM155R71E103KA01D | Murata | 10 nF 10 Murata GRM155R71E103KA01D Digikey 490-1312-1-ND |
| LQG15HN8N2J02D | Murata | L4 8.2 nH 1 Murata LQG15HN8N2J02D Digikey 490-2622-1-ND |
| LQG15HS3N9S02D | Murata | L1, L10 3.9 nH 2 Murata LQG15HS3N9S02D Digikey 490-2617-1-ND |
| LQH31HNR88K03L | Murata | L3, L5, L8 880 nH 3 Murata LQH31HNR88K03L Digikey LQH31HNR88K03 |
| BAP70Q | NXP | U2 BAP70Q 1 NXP BAP70Q NXP BAP70Q |
| BGA3015 | NXP | U3 BGA3015 1 NXP BGA3015 NXP BGA3015 |
| BGA3018 | NXP | U1 BGA3018 1 NXP BGA3018 NXP BGA3018 |
| RC0402FR-070RL | Yageo | R5, R8 0 Ω (Jumper) 2 Yageo RC0402FR-070RL Digikey 311-0.0LRCT-ND |
| RC0402FR-070RL | Yageo | L7 0 Ω (Jumper) 1 Yageo RC0402FR-070RL Digikey 311-0.0LRCT-ND |
| RC0402FR-07300RL | Yageo | R2, R10, R11 300 Ω 3 Yageo RC0402FR-07300RL Digikey 311-300LRCT-ND |
| RC0402FR-07470RL | Yageo | R1, R3, R9 470 Ω 3 Yageo RC0402FR-07470RL Digikey 311-470LRCT-ND |
| 861V509ER6 | Bomar | J1, J2 75Ω F-connector 2 Bomar 861V509ER6 |
| RC0402FR-71K2L | Yageo | R4, R7 1200 Ω 2 Yageo RC0402FR-71K2L |
| RC0402FR-72K2L | Yageo | R6 2200 Ω 1 Yageo RC0402FR-72K2L |
| RC0402FR-71K2L | Yageo | R4, R7 1200 Ω 2 Yageo RC0402FR-71K2L Digikey 311-1.20KLRCT- |
| RC0402FR-72K2L | Yageo | R6 2200 Ω 1 Yageo RC0402FR-72K2L Digikey 311-2.20KLRCT- |