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CISPR 32: Multimedia Equipment – Electromagnetic Compatibility Emission Requirements
Unified EMC emission standard for multimedia equipment covering conducted and radiated emissions from 0.15 MHz to 6 GHz
Introduction to CISPR 32
CISPR 32 is a landmark EMC emission standard that consolidated and superseded several earlier CISPR standards, including CISPR 13 (audio/video equipment emissions), CISPR 22 (ITE emissions), and portions of CISPR 20 (broadcast receiver emissions). Published in 2015, CISPR 32 provides a unified set of emission requirements for multimedia equipment (MME) — a broad category encompassing information technology equipment, audio/video equipment, broadcast receivers, and multimedia devices such as game consoles and streaming devices. The standard covers both conducted emissions (0.15-30 MHz on AC power ports) and radiated emissions (30 MHz to 1 GHz, with extensions to 6 GHz for microwave-band equipment). CISPR 32 represents a significant simplification of the EMC compliance landscape by harmonizing previously separate emission requirements into a single, coherent standard.
CISPR 32 introduces the concept of “multimedia equipment” (MME) which replaces the separate categories of ITE and AV equipment. This reduces compliance complexity for products that combine computing, audio/video, and networking functions — which describes virtually all modern consumer electronics.
Emission Limits and Measurement Methods
CISPR 32 defines emission limits for both Class A (industrial/commercial) and Class B (residential) multimedia equipment. The limits closely follow those of CISPR 22 for ITE but with adjustments for AV-specific port types. A key innovation in CISPR 32 is the introduction of unified measurement methods that apply consistently across all MME types, eliminating the previous situation where AV equipment and ITE were measured differently. The standard specifies both radiated disturbance measurements in the 30-1000 MHz range (with extensions to 6 GHz) and conducted disturbance measurements on AC power ports, wired network ports, and telecom ports. New measurement requirements for broadcast receiver tuner ports and antenna ports are also included, ensuring that the emissions from these ports are properly controlled.
| Emission Type | Class | Frequency Range | Limit (Quasi-Peak) | Measurement Distance |
|---|---|---|---|---|
| Conducted (AC port) | Class B | 0.15 – 0.50 MHz | 66-56 dBµV | — |
| Conducted (AC port) | Class B | 0.50 – 5.0 MHz | 56 dBµV | — |
| Conducted (AC port) | Class B | 5.0 – 30 MHz | 60 dBµV | — |
| Radiated, 30-230 MHz | Class B | 30 – 230 MHz | 40 dBµV/m (at 3 m) | 3 m / 10 m |
| Radiated, 230-1000 MHz | Class B | 230 – 1000 MHz | 47 dBµV/m (at 3 m) | 3 m / 10 m |
| Radiated, 1-3 GHz | Class B | 1 – 3 GHz | 52 dBµV/m (peak) | 3 m |
| Radiated, 3-6 GHz | Class B | 3 – 6 GHz | 54 dBµV/m (peak) | 3 m |
CISPR 32 extends radiated emission measurements up to 6 GHz for equipment with internal clock frequencies above 108 MHz. This extension captures emissions from modern high-speed digital interfaces including HDMI 2.0 (up to 6 GHz), USB 3.0 (up to 5 GHz), and DisplayPort (up to 8.1 GHz).
Engineering Design for CISPR 32 Compliance
Designing multimedia equipment to meet CISPR 32 requires addressing emissions from multiple internal noise sources: switching power supplies, high-speed digital buses (DDR memory, PCI Express, HDMI), wireless transceivers (Wi-Fi, Bluetooth, cellular), and internal clock generation circuits. A systematic approach includes: (1) PCB-level design with continuous ground planes, minimal loop areas for high-speed signals, and proper stack-up orientation; (2) strategic use of spread-spectrum clocking for all clock signals above 10 MHz, providing 8-15 dB peak emission reduction; (3) comprehensive I/O port filtering with common-mode chokes, ferrite beads, and decoupling capacitors tailored to each port’s signal characteristics; and (4) enclosure shielding with conductive gaskets or finger stock at seam intervals ≤ λ/20 at 1 GHz (approximately 15 mm).
For wireless-enabled multimedia devices, co-existence engineering is critical. The internal emissions from high-speed digital circuits must not desensitize the device’s own wireless receivers. This requires careful physical separation of antennas from noise sources (minimum 20 mm recommended), use of shielded cans over WLAN/BT modules, and filtering of power supply noise on the RF supply rails. Pre-compliance testing using a near-field scanner and spectrum analyzer during development can identify emission hot spots — typically at cable exit points, enclosure seams, and around high-speed connectors — before formal EMC testing.
A systematic pre-compliance program using a GTEM cell or fully anechoic chamber can reduce CISPR 32 compliance testing costs by 40-60% by identifying and fixing emission issues before the first formal laboratory test. Most compliance failures are caused by cable radiation (35%), enclosure seam leakage (25%), and power supply harmonics (20%).
Transition from CISPR 22 and CISPR 13
CISPR 32 represents a significant regulatory change, replacing CISPR 22 (ITE) and CISPR 13 (AV equipment) with a unified standard. For manufacturers who previously designed products to CISPR 22 or CISPR 13 separately, the transition to CISPR 32 requires careful evaluation of existing designs. While the limits are similar, the measurement methods have been harmonized — AV equipment previously tested to CISPR 13 must now follow CISPR 32 procedures, which may reveal emissions that were previously masked by different measurement bandwidths or detector characteristics. The standard includes transition provisions allowing dual-compliance declarations during the phase-out period of the earlier standards.
Products that were compliant with CISPR 22 or CISPR 13 may not automatically comply with CISPR 32 due to differences in measurement methods, especially for radiated emissions above 1 GHz and conducted emissions on telecom ports. A re-assessment of existing designs is strongly recommended.
Frequently Asked Questions
Q: Does CISPR 32 apply to products with wireless charging?
A: Yes, wireless charging transmitters in multimedia equipment are covered. The charging coil and its drive circuit can be significant sources of magnetic field emissions that must be measured within the standard’s framework.
A: Yes, wireless charging transmitters in multimedia equipment are covered. The charging coil and its drive circuit can be significant sources of magnetic field emissions that must be measured within the standard’s framework.
Q: What is the difference between CISPR 32 radiated limits at 3 m and 10 m?
A> The limits are distance-scaled using the inverse-distance law (20 dB/decade). A 40 dBµV/m limit at 3 m is equivalent to 30 dBµV/m at 10 m for far-field measurements. The 3 m method is more commonly used in modern test facilities.
A> The limits are distance-scaled using the inverse-distance law (20 dB/decade). A 40 dBµV/m limit at 3 m is equivalent to 30 dBµV/m at 10 m for far-field measurements. The 3 m method is more commonly used in modern test facilities.
Q: How do I measure emissions from a product with an integral antenna?
A> The product is tested as a complete system in normal operating mode. For intentional radiators (Wi-Fi, Bluetooth), the transmitter is activated in continuous transmission mode while the rest of the system operates in a representative worst-case configuration.
A> The product is tested as a complete system in normal operating mode. For intentional radiators (Wi-Fi, Bluetooth), the transmitter is activated in continuous transmission mode while the rest of the system operates in a representative worst-case configuration.
Q: What is the significance of the 6 GHz measurement extension?
A> Products with internal clock frequencies above 108 MHz or utilizing microwave-band wireless technologies (60 GHz Wi-Fi, automotive radar) require radiated emission measurements up to 6 GHz. This captures harmonics of high-speed digital interfaces and local oscillator leakage.
A> Products with internal clock frequencies above 108 MHz or utilizing microwave-band wireless technologies (60 GHz Wi-Fi, automotive radar) require radiated emission measurements up to 6 GHz. This captures harmonics of high-speed digital interfaces and local oscillator leakage.
