Zero-Bias Schottky vs Tunnel Diode Detector | Herotek RF Detector Selection
Herotek offers both zero-bias Schottky diode detectors and tunnel diode detectors for RF, microwave and millimeter-wave signal monitoring. Both technologies operate without an external bias supply, but they are optimized for different measurement requirements.
Zero-bias Schottky detectors are generally selected for wide frequency coverage, controlled RF input matching and higher continuous-wave input power. Tunnel diode detectors are particularly useful when fast pulse response, low output resistance and low-frequency video performance are priorities.
Main Differences
| Selection Factor | Zero-Bias Schottky Detector | Tunnel Diode Detector |
| External Bias | Not required | Not required |
| Herotek Frequency Coverage | 100kHz–50GHz | 0.1–40GHz |
| Maximum CW Input Power | Up to 200mW for DZR and DZM series | 50mW |
| Pulse Response | Depends on model and output circuit | Less than 5ns typical rise time |
| RF Input Match | DZR and DZM series feature matched inputs | Typical VSWR varies by model |
| Output Resistance | Depends on model and load | 125Ω typical |
| Key Strength | Wideband monitoring and flat response | Fast pulse detection |
| Typical Applications | Test equipment, transmitter and power monitoring | Radar, pulse monitoring and guidance systems |
Herotek specifies matched inputs, flat frequency response and up to 200mW CW input power for its DZR and DZM zero-bias Schottky detector families. Its tunnel diode detectors provide a typical output resistance of 125Ω, a typical rise time below 5ns and a maximum CW input power of 50mW.
When to Choose a Zero-Bias Schottky Detector
A Herotek zero-bias Schottky detector is usually the more suitable choice when the application requires:
Broad frequency coverage extending to 50GHz
A well-matched RF input
Low VSWR across a wide operating band
Flat frequency response
Up to 200mW continuous-wave input power
Microwave or millimeter-wave signal monitoring
The DZR series operates over temperature from −55°C to +100°C and provides standard negative output polarity. A positive-output version can be specified by adding the suffix P to the model number.
Recommended Herotek Zero-Bias Models
| Model | Frequency Range | RF Input | Main Selection Reason |
| DZR124AA | 10MHz–12.4GHz | SMA male | Tight ±0.3dB full-band flatness |
| DZR185AA | 10MHz–18.5GHz | SMA male | General-purpose broadband monitoring |
| DZR265AA | 10MHz–26.5GHz | SMA male | SMA-connected operation to 26.5GHz |
| DZR400KA | 10MHz–40GHz | 2.9mm K male | Broadband microwave detection to 40GHz |
| DZR50024A | 10MHz–50GHz | 2.4mm male | Millimeter-wave monitoring to 50GHz |
When to Choose a Tunnel Diode Detector
A Herotek tunnel diode detector should be considered when the application requires:
Fast microwave pulse detection
Less than 5ns typical rise time
Low output resistance
Low 1/f noise
Stable response over a wide temperature range
Radar or pulsed-transmitter monitoring
These characteristics make tunnel diode detectors particularly useful in systems where the detector must follow short pulses or rapidly changing RF envelopes. Herotek specifies typical temperature stability of ±0.5dB over temperature extremes for the tunnel detector family.
Recommended Herotek Tunnel Diode Models
| Model | Frequency Range | Minimum Sensitivity | Main Selection Reason |
| DT1012 | 1–12GHz | 750mV/mW | Broadband detection below 12GHz |
| DT1018 | 1–18GHz | 700mV/mW | Full 1–18GHz pulse detection |
| DT1026 | 1–26.5GHz | 400mV/mW | Extended microwave coverage |
| DT1840 | 18–40GHz | 300mV/mW | High-frequency detector for 18–40GHz |
| DT1-40 | 1–40GHz | 250mV/mW | Ultra-wideband tunnel diode detection |
Ordering Information
DataStorageIC supports international inquiries for Herotek zero-bias Schottky and tunnel diode detectors, including:
Herotek detector price and availability
Datasheet and technical specification requests
DZR400KA, DZR50024A and DT1018 quotations
Positive-output detector versions
Detector model comparison
International RFQ and delivery support
Please provide the model number, required quantity, destination country and expected delivery date when requesting a quotation.
Frequently Asked Questions
Do both detector types require an external bias supply?
No. Herotek zero-bias Schottky and tunnel diode detectors are designed to operate without an external bias supply.
Which detector is better for fast RF pulses?
A tunnel diode detector is generally the preferred choice. Herotek specifies a typical rise time of less than 5ns for its tunnel diode detector family.
Which detector supports the highest frequency?
Herotek zero-bias Schottky detectors extend to 50GHz with models such as the DZR50024A. The standard tunnel diode detector range extends to 40GHz.
Which detector handles more continuous-wave input power?
Herotek DZR and DZM zero-bias Schottky detectors are rated for up to 200mW CW. Tunnel diode detectors are rated for a maximum of 50mW CW.
Can the sensitivity specifications be compared directly?
Not always. Schottky and tunnel detector datasheets may specify sensitivity using different units, input levels and measurement conditions. Selection should be based on the complete application requirements.
Are positive-output versions available?
Yes. Negative output polarity is standard. Adding the suffix “P” to the applicable Herotek model number specifies positive output polarity.
