SNA DBridge
This page describes the Directional Bridge for the rev0SNA 50-2500 MHz Scalar Network Analyzer.
Summary
The Directional Bridge is based around a wideband balun and precision RF resistors. Two baluns chosen for evaulation, the Mini-Circuits TCM1-43X+, which features an amplitude balance of <0.5dB and phase balance of <7 degrees across the 50-2500 MHz operating range, and the Coilcraft JA-4220, which features an insertion loss of <2dB across the 50-2500 MHz operating range. The bridge resistors chosen are Vishay FC0402E50R0BTBST1 0402 flip chip precision 50 ohm 10 GHz RF resistors. The layout was done to minimize distances and match distances between the resistors in the bridge. The performance will largely be limited by the assembly of the RF transformer and quality with regard to phase and amplitude balance.
Testing
- 12.x.2013: The PCB was assembled and tested for basic functionality by measuring coupled power with and without a load attached.
Revisions
- 1.0: Initial revision using JA-4220 balun.
- 1.1: Second revision using TCM1-43X+ balun.
Bill of Materials (v1.0)
| Part | Quantity | Unit Cost | Total Cost | Source |
| ADL5513 | 1 | $11.36 | $11.36 | Digi-Key |
| ADP124 | 1 | $1.95 | $1.95 | Digi-Key |
| AP1115 | 1 | $0.54 | $0.54 | Digi-Key |
| 0402 100nF Capacitor | 2 | $0.011 | $0.11 | Digi-Key |
| 0402 10pF Capacitor | 2 | $0.0116 | $0.12 | Digi-Key |
| 0402 33nF Capacitor | 2 | $0.024 | $0.05 | Digi-Key |
| 0603 4.7uF Capacitor | 3 | $0.1484 | $0.45 | Digi-Key |
| 0805 10uF Capacitor | 1 | $0.30 | $0.30 | Digi-Key |
| 0603 Capacitor | 1 | $0.0096 | $0.01 | eBay - mib_instruments |
| 0603 Resistor | 2 | $0.00294 | $0.01 | eBay - mib_instruments |
| 0402 Resistor | 1 | $0.025 | $0.03 | eBay - mib_instruments |
| 0603 Ferrite Bead (470 Ohm) | 1 | $0.0472 | $0.05 | Digi-Key |
| Male Header | 3 | $0.01 | $0.03 | eBay |
| SMA Female Connector | 1 | $3.37 | $3.37 | Digi-Key |
| SMA Female Connector | 1/5 | $2.51 | $0.50 | Dealextreme |
| PCB | 0.675"x0.75"/3 | $10.00 | $1.69 | Laen's PCB |
| Total Unit Cost | $20.57 |
PCB/Construction Photos
- Rev0VTx VCO PCB Bottom.jpg
Bottom of unpopulated PCB
- Rev0VTx VCO PCB Top.jpg
Top of unpopulated PCB
- Rev0VTx VCO Top.jpg
Populated PCB