Part A
ADF4157BCPZ
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 6114 PCS
- Package
- WFQFN-20
- Series
- Horloge Timing - générateur d'horloge, PLL, synthétiseur de fréquence
Replacement verdict
Compatible functional replacement candidate
The ADF4157BCPZ and ADF4154BCPZ-RL are both fractional-N PLL frequency synthesizers from Analog Devices in the same 20-lead LFCSP package, sharing a common supply range and 4.0 GHz maximum RF input. The ADF4154BCPZ-RL offers a higher maximum phase detector frequency and a wider operating temperature range, while the ADF4157BCPZ provides a higher fractional modulus for finer frequency resolution. Both are functionally comparable synthesizers, but the differences in phase detector frequency, fractional resolution, and temperature rating require design validation before substitution.
Package Type
High match
Supply Voltage Range
High match
Maximum Phase Detector Frequency
Validation required
Operating Temperature Range
Not compatible
Parts at a glance
Part B
ADF4154BCPZ-RL
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 7852 PCS
- Package
- WFQFN-20
- Series
- Horloge Timing - générateur d'horloge, PLL, synthétiseur de fréquence
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADF4157BCPZ | ADF4154BCPZ-RL | Why it matters |
|---|---|---|---|
| Maximum RF Input Frequency | 6 GHz | 4 GHz | Determines the highest frequency the PLL can synthesize; the ADF4157 supports higher-frequency applications. |
| Maximum PFD Frequency | 32 MHz | 32 MHz | Sets the phase frequency detector rate, which affects phase noise and loop bandwidth capability. |
| Modulus (Fractional Resolution) | 2^25 (33,554,432) | 2^25 (33,554,432) | Higher modulus enables finer frequency resolution in fractional-N synthesis. |
| Normalized Phase Noise Floor | -220 dBc/Hz | -216 dBc/Hz | Lower phase noise floor yields cleaner output signals, critical for high-performance RF systems. |
| Supply Voltage Range | 2.7 V to 3.3 V | 2.7 V to 3.3 V | Defines the operating voltage window; both parts are compatible with common 3 V rails. |
| Package | 20-Lead LFCSP (4x4 mm) | 20-Lead LFCSP (4x4 mm) | Package footprint and thermal characteristics affect PCB layout and assembly compatibility. |
| Charge Pump Current Range | 0.3 mA to 5 mA | 0.3 mA to 5 mA | Charge pump current influences loop filter design and lock time performance. |
| Operating Temperature Range | -40°C to +85°C | -40°C to +85°C | Determines environmental suitability for industrial and commercial applications. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADF4157BCPZ | ADF4154BCPZ-RL |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Type | Fractional N Synthesizer (RF) | Fractional N Synthesizer (RF) |
| PLL | Yes | Yes |
| Input | CMOS, TTL | CMOS, TTL |
| Output | Clock | Clock |
| Number of Circuits | 1 | 1 |
| Ratio - Input: Output | 2:1 | 2:1 |
| Differential - Input: Output | Yes/No | Yes/No |
| Frequency - Max | 6GHz | 4GHz |
| Divider / Multiplier | Yes/Yes | No/Yes |
| Voltage - Supply | 2.7V ~ 3.3V | 2.7V ~ 3.3V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the key differences between the ADF4157BCPZ and ADF4154BCPZ-RL?
The ADF4157BCPZ is a 6 GHz fractional-N PLL synthesizer with a 25-bit fixed modulus, while the ADF4154BCPZ-RL is a 4 GHz fractional-N PLL synthesizer with a programmable modulus. The ADF4157 offers higher frequency operation and a fixed modulus architecture, whereas the ADF4154 provides lower frequency operation with a programmable fractional modulus and integrated VCO divider options.
Are the ADF4157BCPZ and ADF4154BCPZ-RL pin-compatible?
No. Both devices are offered in a 20-lead LFCSP package, but the pin functions and register maps differ between the two products. The ADF4157BCPZ and ADF4154BCPZ-RL are not direct pin-for-pin replacements, and the PCB layout and control software must be validated separately for each device.
What is the maximum RF output frequency of each device?
The ADF4157BCPZ supports RF output frequencies up to 6 GHz. The ADF4154BCPZ-RL supports RF output frequencies up to 4 GHz. The applicable frequency range depends on the external VCO and loop filter used in the design.
What is the difference in fractional modulus between the two parts?
The ADF4157BCPZ uses a 25-bit fixed modulus fractional-N architecture. The ADF4154BCPZ-RL uses a programmable fractional modulus. This difference affects spurious performance, resolution, and the register configuration required in firmware.
Do both devices use the same supply voltage and interface?
Both the ADF4157BCPZ and ADF4154BCPZ-RL operate from a 2.7 V to 3.3 V supply and use a 3-wire SPI-compatible serial interface for register programming. However, the register maps and bit definitions differ, so firmware written for one device cannot be used unchanged on the other.
Can the ADF4154BCPZ-RL be used as a drop-in replacement for the ADF4157BCPZ?
No. Because the two devices differ in maximum frequency, fractional modulus architecture, and register map, the ADF4154BCPZ-RL is not a drop-in replacement for the ADF4157BCPZ. Any substitution requires revalidation of the RF design, loop filter, and control software against the manufacturer datasheet.
What package do both devices use?
Both the ADF4157BCPZ and ADF4154BCPZ-RL are supplied in a 20-lead LFCSP package. The "-RL" suffix on the ADF4154BCPZ-RL indicates tape-and-reel packaging. Designers should confirm package and ordering details against the official manufacturer datasheet before production.