Part A
ADF41020BCPZ
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 4229 個数
- Package
- WFQFN-20
- Series
- クロックタイミング - クロックジェネレータ、PLL、周波数シンセサイザ
Replacement verdict
Not a drop-in replacement
The ADF4156BCPZ and ADF41020BCPZ are not functionally interchangeable: they differ in maximum operating frequency, RF input frequency range, and phase detector frequency, and they use different package footprints. The ADF4156BCPZ is a fractional-N synthesizer suited to lower-frequency, fine-resolution applications, while the ADF41020BCPZ is an integer-N PLL targeting higher-frequency designs. Substitution would require a full redesign of the frequency plan, loop filter, and board layout, so these parts should not be treated as drop-in replacements.
Different maximum frequency
Different RF input range
Different phase detector frequency
Different package footprint
Parts at a glance
Part B
ADF4156BCPZ
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 1350 個数
- Package
- WFQFN-20
- Series
- クロックタイミング - クロックジェネレータ、PLL、周波数シンセサイザ
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADF4156BCPZ | ADF41020BCPZ | Why it matters |
|---|---|---|---|
| Maximum Operating Frequency | 6 GHz | 18 GHz | Determines the highest RF input frequency the PLL can synthesize; the ADF41020 supports much higher frequency bands, so it is not a drop-in replacement for high-band applications. |
| PLL Type / Function | Fractional-N frequency synthesizer | Integer-N frequency synthesizer | Fractional-N allows finer frequency resolution and lower phase noise for a given reference, while integer-N is simpler; the architectures are fundamentally different and affect loop filter design and spurious performance. |
| RF Input Frequency Range | 500 MHz to 6 GHz | 1 GHz to 18 GHz | Defines the usable band of the synthesizer; the two parts cover largely non-overlapping ranges, limiting direct substitutability. |
| Maximum RF Input Frequency (Prescaler) | 6 GHz | 18 GHz | The integrated prescaler sets the upper frequency limit; the ADF41020's higher-rated prescaler enables microwave operation not possible with the ADF4156. |
| Supply Voltage Range | 2.7 V to 3.3 V | 2.7 V to 3.3 V (analog/digital), charge pump up to 5.5 V | Both operate from a similar low-voltage core supply, but the ADF41020's extended charge pump supply allows higher tuning voltages, affecting VCO compatibility. |
| Package | 20-lead LFCSP (4 mm x 4 mm) | 20-lead LFCSP (4 mm x 4 mm) | Identical package footprint and pin count simplify board-level replacement, though pin functions and firmware must still be verified. |
| Charge Pump Current (Programmable) | Up to 5 mA | Up to 5 mA | Charge pump current sets loop bandwidth and phase noise; matching values ease loop filter reuse, but register maps differ between the two parts. |
| Control Interface | 3-wire SPI (serial) | 3-wire SPI (serial) | Both use a similar serial programming interface, but register definitions and bit widths differ, so firmware is not directly interchangeable. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical industrial temperature ratings mean both suit the same environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADF41020BCPZ | ADF4156BCPZ |
|---|---|---|
| Part Status | Last Time Buy | Active |
| Type | Clock/Frequency Synthesizer (RF) | Fractional N Synthesizer (RF) |
| PLL | Yes with Bypass | Yes |
| Input | CMOS, TTL | CMOS, TTL |
| Output | Clock | Clock |
| Number of Circuits | 1 | 1 |
| Ratio - Input: Output | 2:1 | 2:1 |
| Differential - Input: Output | No/No | Yes/No |
| Frequency - Max | 18GHz | 6.2GHz |
| Divider / Multiplier | Yes/No | Yes/Yes |
| Voltage - Supply | 2.85V ~ 3.15V | 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 primary functional differences between the ADF4156BCPZ and the ADF41020BCPZ?
The ADF4156BCPZ is a fractional-N frequency synthesizer with an integrated voltage-controlled oscillator (VCO) covering 6 GHz, while the ADF41020BCPZ is a 20 GHz integer-N PLL frequency synthesizer without an integrated VCO. The ADF4156BCPZ supports fractional-N operation for finer frequency resolution, whereas the ADF41020BCPZ is designed for high-frequency integer-N applications up to 20 GHz.
What is the maximum operating frequency of each device?
The ADF4156BCPZ integrates a VCO with a fundamental output range of 6 GHz, and its RF input can accept signals up to 6 GHz. The ADF41020BCPZ supports RF input frequencies up to 20 GHz, making it suitable for higher-frequency microwave applications.
Do both devices use the same package and pinout?
Both the ADF4156BCPZ and ADF41020BCPZ are offered in a 20-lead LFCSP package. However, the pin functions and internal architecture differ because the ADF4156BCPZ includes an integrated VCO and fractional-N modulator, while the ADF41020BCPZ is an integer-N PLL without a VCO. Therefore, they are not pin-for-pin drop-in replacements despite sharing the same package footprint.
Which device is better suited for low phase noise microwave synthesis?
The ADF41020BCPZ is specified for operation up to 20 GHz and is intended for high-frequency integer-N PLL applications where an external VCO is used, allowing selection of a low-phase-noise VCO for the target band. The ADF4156BCPZ integrates a 6 GHz VCO and is optimized for fractional-N synthesis below 6 GHz. The better choice depends on the required frequency band and whether fractional resolution is needed.
What is the key difference in division architecture between the two parts?
The ADF4156BCPZ uses a fractional-N architecture with a programmable modulus, enabling frequency resolution finer than the phase detector frequency. The ADF41020BCPZ uses an integer-N architecture with a dual-modulus prescaler, so its output frequency resolution equals the phase detector comparison frequency. This architectural difference affects spurious performance, lock time, and frequency step size.
Can the ADF4156BCPZ and ADF41020BCPZ share the same reference input and control interface?
Both devices support a CMOS-compatible reference input and a serial interface for register programming, but their register maps, bit definitions, and programming sequences are device-specific and not interchangeable. The reference input frequency range and interface timing must be verified separately against each datasheet before sharing a common reference or microcontroller interface.
Are these devices interchangeable in an existing design?
No. The ADF4156BCPZ and ADF41020BCPZ differ in frequency range, PLL architecture (fractional-N versus integer-N), VCO integration, register map, and external component requirements. A direct substitution is not possible without redesigning the loop filter, verifying the reference and RF input paths, and updating the programming sequence according to the respective datasheet.