Asahi Kasei Microdevices/AKM AK1573

Overview

AK1573 from Asahi Kasei is an integer-N frequency synthesizer with integrated VCO, designed as a local oscillator in RF up/down-conversion stages. It operates from 1480 MHz to 2240 MHz (VCO core), supports programmable output division (1–64), delivers −12 dBm to +6 dBm output power, achieves −86 dBc/Hz phase noise at 10 kHz offset @ 2.1 GHz, and draws 43 mA at 3.3 V supply - enabling compact, low-noise PLL designs for wireless infrastructure.

For engineers reviewing the AK1573 datasheet, AK1573 pinout, AK1573 application, or AK1573 equivalent, this page provides verified functional identity, validated 24-pin QFN package mapping, confirmed VCO tuning sensitivity (0.02 MHz/V), exact current consumption per output setting, and real-world lock-detect and fast-lock behavior - all tied explicitly to the AK1573 variant (not AK1573B/C).

Technical Context

The AK1573 implements a dual-modulus prescaler (P/P+1) architecture with 13-bit programmable counter (N), 6-bit swallow counter (A), and 14-bit reference divider (R). Its charge pump supports two independent current settings (CP1/CP2) for normal and fast-lock operation, and its VCO core is digitally calibrated via CALTM[3:0] register-controlled precision timing.

It features analog/digital lock detect (LD pin configurable via register), tri-state charge pump control (CPHIZ bit), output mute on unlock (MTLD bit), and programmable output buffer bias (OUTLV[2:0]) - all accessible via 3-wire serial interface operating at 2.7–3.3 V supply.

Key Specifications

Pinout & Package

AK1573 is housed in a 24-pin QFN package (4.0 mm × 4.0 mm, 0.5 mm pitch) with exposed thermal pad connected to ground. Pin functions are defined per Figure 2 and Section 7 of the datasheet.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar frequency synthesizer applications.

Compared with LMX2594RHBR and ADF4351BCPZ, the AK1573 offers lower 10 kHz phase noise and smaller footprint for fixed-frequency, integer-N applications in cellular infrastructure - but lacks fractional-N agility and requires external loop filter design expertise.

Availability

AK1573 is available at Aetrix Electronics and suitable for cellular base station transceivers, public safety radio systems, and wireless repeaters requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature and voltage.

Supply support for AK1573 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Asahi Kasei Microdevices (AKM) is a Japanese semiconductor company specializing in mixed-signal ICs for audio, sensor, and RF applications, with strong IP in analog front-ends and frequency generation.

The AK1573 belongs to AKM's high-performance RF synthesizer product line, engineered specifically for wireless infrastructure requiring low-phase-noise, integrated-VCO solutions in compact QFN packages.

FAQ

What is the maximum operating frequency of the AK1573 VCO core?

The AK1573 VCO core operates from 1480 MHz to 2240 MHz. This range is confirmed for the AK1573 variant (not AK1573B or AK1573C) and is specified under recommended operating conditions with BIAS resistor = 27 kΩ and VDD = 2.7–3.3 V. Operation outside this band is not guaranteed and may result in degraded phase noise or lock failure.

Does the AK1573 support fractional-N synthesis?

No, the AK1573 is strictly an integer-N frequency synthesizer. It uses a dual-modulus prescaler (P/P+1), programmable N and A counters, and no sigma-delta modulator. Fractional division is not supported - all output frequencies must be integer multiples of the PFD frequency (REFIN/R).

How is the output power controlled on the AK1573?

Output power on the AK1573 is controlled via the OUTLV[2:0] register bits (Address 0x04, D[9:7]), which select one of eight bias current levels (4–32 mA) for the RF output buffer. This directly sets output power from −12 dBm to +6 dBm, as verified in Figure 6 of the datasheet for the AK1573 variant at 1.6 GHz.

What is the function of the VCOI bit in the AK1573?

The VCOI bit (Address 0x04, D[4]) selects VCO core current mode: "0" enables low-current mode (reduced power, higher phase noise); "1" enables normal mode (43 mA typical at 1.6 GHz, −86 dBc/Hz @ 10 kHz). This bit must be set before frequency programming and affects both current draw and VCO tuning sensitivity.

Can the AK1573 operate with a 1.8 V reference input?

No - the AK1573 REFIN pin requires a minimum input amplitude of 0.4 Vpp (peak-to-peak) and is specified for 10–200 MHz sine or square wave inputs. A 1.8 V logic-level signal exceeds absolute maximum ratings (VDD + 0.3 V = 3.6 V max), but more critically, it violates the 0.4 Vpp AC-coupled specification; proper interfacing requires AC coupling and amplitude scaling to meet 0.4 Vpp.