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Multiple models covered + metrics measured in real-world conditions! The domestically produced Bias-T rivals imported models—replacement is effortless!
Release time:
2026-03-06 17:07
Source:
Zhongwei Puyi
I. Zhongwei Puyue’s Partial Bias-T (Benchmarking SHF and Foucs)
Currently, our company has developed the following models of Bias-T:
Partial device display:
II. Definitions and Operating Principles
Bias-T (DC biaser) It is a three-port passive network device whose three ports are the radio frequency port RF, the DC bias port DC, and the RF-plus-DC common port Common (RF+DC). These three ports are typically arranged in a T-shape, hence the name "Bias-T." This device can be applied across all fields—from chips to test, measurement equipment, and systems.
The Bias-T incorporates capacitors and inductors internally. The capacitor blocks DC current while allowing AC signals to pass through; at the RF end, it receives RF signals from the DUT but does not allow any DC current to flow from the DC end. On the other hand, the inductor behaves oppositely: it allows DC power to be supplied to the DUT while simultaneously preventing the DC power supply from being disturbed by RF signals returning from the common terminal. In this way, the Bias-T ensures that DC power is delivered to the load without interfering with the normal transmission of AC signals. Without such isolation, both the device’s power supply and its RF signals could be damaged. Moreover, thanks to its built-in voltage and current stabilization functions, the Bias-T can partially offset external disturbances such as voltage fluctuations and ambient temperature changes.
III. Key Specifications of the Bias-T (BT67A)
In RF circuits, the Bias-T serves as a critical component; the quality of its specifications directly affects circuit performance and even device safety. Specific data tests can more clearly demonstrate the advantages of the BT67A.
1. Operating frequency range
The frequency range over which a bias-T can operate stably depends on the RF signal frequency. For example, satellite communications may require coverage of the Ku-band (12–18 GHz). The bias-T must be matched to the system’s RF signal frequency; exceeding this range will lead to a dramatic increase in signal attenuation and phase distortion. Zhongwei Puyue offers a selection of frequency bands ranging from 50 kHz to 110 GHz.
2. DC-side DC current/resistance/voltage
1). Direct current
The maximum continuous DC current that the DC side can safely handle must match the operating current of the load device. Exceeding this maximum value can cause the device to overheat and burn out. The load current should be ≤ 80% of the device’s maximum DC current (allowing for a margin to avoid overload).
2). DC resistance
The equivalent resistance of the DC channel is primarily determined by the wire resistance of the internal inductance. The lower the DC resistance, the smaller the power loss (P = I²R), thus avoiding insufficient supply voltage to the load devices due to voltage drop.
3). DC voltage
The maximum DC voltage that the DC end can withstand, ensuring that the power supply voltage does not cause breakdown of components such as the DC-blocking capacitor inside the Bias-T.
4) DC pulse signal
The Bias-T enables DC pulse signal power supply. At its core, it leverages the frequency characteristics of its own inductor and capacitor to allow DC pulses and RF signals to be transmitted independently on the same transmission line without interfering with each other. The peak current and voltage of the DC pulses must not exceed the Bias-T’s maximum rated DC current and voltage.
3. Isolation between the RF and DC ports
Isolation primarily measures the effectiveness of an inductor coil in blocking radio-frequency signals. The higher the isolation, the less likely RF signals are to interfere with the power supply system. If a Bias-T device has poor isolation performance, RF signals can leak into the power supply system, thereby affecting system performance. At 67 GHz, the BT67A exhibits an isolation level of approximately -50 dB. If a 2-W RF signal is input at the RF end at this specific frequency, only about 0.2 mW of interference will be detected at the DC end.
4. Insertion Loss
Insertion loss refers to the amount of signal attenuation between the RF port and the common port. The smaller the absolute value of the insertion loss, the better the performance. In the full frequency band of the BT67A, the maximum insertion loss is below 1.75 dB, indicating minimal signal attenuation and excellent transmission performance of the device for low-frequency RF signals.
5. Voltage Standing Wave Ratio (VSWR)
The Voltage Standing Wave Ratio (VSWR) is a metric used to measure impedance matching. The lower the VSWR value, the better the impedance match and the less signal reflection and distortion there will be. When the VSWR is 1, it indicates that there is no signal reflection; when the VSWR is 1.2, the reflection rate is 0.83%; and when the VSWR is 1.5, the reflection rate is 4%.
The standing-wave ratio (SWR) of the BT67A varies throughout the entire band. When used over a wide frequency range, the SWR changes with frequency; therefore, impedance matching should be optimized as much as possible across the broad frequency range.
6. Group Delay
Group delay reflects the degree of phase distortion introduced when a signal passes through a bias-T network. The smaller the variation in group delay, the less impact the signal will have—meaning that all frequency components experience the same delay, and no phase distortion occurs after the signal passes through the system. Ideally, the group delay curve should be a straight line with no fluctuations. As observed on the oscilloscope, the overall group delay fluctuates within the range of 40–60 ps, with no obvious trend of monotonic increase or decrease with frequency. These small-scale fluctuations remain within the system’s allowable tolerance and do not affect the overall system performance.
4. Benchmark against SHF (BT65R) and MARKI (BT-0065)
1. Relevant indicators
2. Comparison of Eye Diagrams Between BT65R and BT67A
The Bias-T developed by Zhongwei Puyee— The maximum frequency of BT110A has reached 110 GHz. ， It can substitute for foreign SHF and MARKI products, with performance indicators superior to those of its peers. Moreover, it has successfully completed all required environmental tests, meeting the specified standards (including 1-hour dielectric strength test, 168-hour current endurance test, high- and low-temperature tests ranging from -20°C to 60°C, and vibration testing).
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